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We present the design performance validation of an energy-efficient silicon Mach-Zehnder modulator (MZM) with a forward-biased PIN junction by simulation and experiment. With a length of $50~\mu \text{m}$ , the presented MZM exhibits at least four times smaller form factor for the active phase-shifter than the state-of-the-art. Furthermore, we recorded a remarkably low $V_{\mathrm {\pi }}L$ of only 0.0025 $\text{V}\times $ cm. By thermal tuning of an additional heater, segmented with the phase shifter, the measured DC extinction ratio of the MZM was 30 dB. Non-return-to-zero data transmission up to 5 Gb/s and the generation of sinc-shaped Nyquist pulse sequences with a bandwidth of 12 GHz is demonstrated. The very small footprint and power consumption make the presented MZM an ideal choice for various applications like Nyquist pulse generation, parallel analog signal processing, arbitrary waveform generation, etc.

This paper introduces a photonics-assisted receiver that enables the reception of high-bandwidth wireless signals with low-bandwidth electronics. The receiver down-converts the input signal into parallel low-bandwidth sub-signals, employing photonics-based orthogonal sampling. This sampling is based on a multiplication and not switching, so, it does not introduce additional aperture jitter. Therefore, the photonics-assisted analog-to-digital converter (ADC) converts the wireless signal with a higher signal-to-noise-and-distortion ratio (SINAD), which improves the Q-factor for the detection. This Q-factor improvement is especially high, when the orthogonal sampling is carried out with low-jitter oscillators. Compared to the direct detection with 30 GHz, the simulation demonstrates a 2.2 dB Q-factor enhancement for the detection of a 30 GHz signal, with 10 GHz electronics. The same improvement is revealed in the experiment for the detection of 12 GHz signals with 4 GHz electronics.

We present a broadband coherent orthogonal frequency-division multiplexing (OFDM) transceiver based on orthogonal sampling and low bandwidth electronic analog signal processing. Wideband superchannels, without any guardband are aggregated from low bandwidth OFDM channels in the time domain by orthogonal Nyquist sinc-pulse sequences with a rectangular bandwidth. Therefore, the method is called OFDM-Nyquist-time division multiplexing (TDM). Simulation and experimental results will be discussed for optical systems. However, with some modifications the same principle can be used for wireless or THz signals. In simulations, we show a 40 GHz bandwidth, 160 Gbps, 16-QAM, 128 OFDM x 5-Nyquist-TDM transceiver based on 4 GHz electronics for the digital-to-analog (DAC), analog-to-digital (ADC) conversion and for the digital signal processing, including Fourier transform. For the experiment, we verify the processing of a 24 GHz bandwidth, 48 Gbps QPSK, 512 OFDM x 3-Nyquist-TDM signal with a 4 GHz transmitter and receiver. Since the proposed method drastically decreases the sampling rate and bandwidth requirements for the Fourier processing, the DAC and ADC, it can be a promising alternative for future communication systems with the highest possible symbol rate.

High-bandwidth signals are needed in many applications like radar, sensing, measurement and communications. Especially in optical networks, the sampling rate and analog bandwidth of digital-to-analog converters (DACs) is a bottleneck for further increasing data rates. To circumvent the sampling rate and bandwidth problem of electronic DACs, we demonstrate the generation of wide-band signals with low-bandwidth electronics. This generation is based on orthogonal sampling with sinc-pulse sequences in ${N}$ parallel branches. The method not only reduces the sampling rate and bandwidth, at the same time the effective number of bits (ENOB) is improved, dramatically reducing the requirements on the electronic signal processing. In proof of concept experiments the generation of analog signals, as well as Nyquist shaped and normal data will be shown. In simulations we investigate the performance of 60 GHz data generation by 20 and 12 GHz electronics. The method can easily be integrated together with already existing electronic DAC designs and would be of great interest for all high-bandwidth applications.

Spectrally efficient modulation formats become essential for optical network scaling as the demand for routed data streams exceeds the present wavelength-division multiplexing systems’ throughput. However, achieving high spectral efficiency at high data rates requires complex and bandwidth-intensive electronics. In this study, we propose an all-optical aggregation scheme that combines multiple low spectral efficiency optical wavelength channels from an optical frequency comb based transmitter into fewer channels with higher spectral efficiency. Our method utilizes coherent spectral superposition and optical vector summation, eliminating the need for optical nonlinearities and relying on linear signal processing with an electro-optic modulator. By adjusting the phase of the radio frequency signal driving the modulator, we can easily achieve the required optical phase tuning for vector addition in the I-Q plane. Through experimental demonstrations, we show that the proposed approach enables the generation of 10 GBd PAM-4 and 10 GBd quadrature phase shift keying (QPSK) signals by aggregating two 10 GBd binary phase shift keying signals. Similarly, we aggregate two 10 GBd QPSK signals into one 10 GBd quadrature amplitude modulation-16 (QAM-16) signal. The experiments employ both conventional and sinc-shaped Nyquist signals. Our in-line, all-optical aggregation concept significantly enhances operational capacity while reducing complexity. It offers a promising solution for realizing flexible integrated optical transmitters for advanced modulation format signals using lower-quality electronics. Additionally, it aligns with the requirements of future dynamically reconfigurable optical networks that leverage spectral traffic aggregation. Given its reliance on linear signal processing with an electro-optic modulator, the integration of the method into any integrated photonic platform is straightforward.

Nicotinic acetylcholine receptors (nAChRs) are involved in various central nervous system functions and have also been implicated in several neurodegenerative disorders. The heteromeric α4β2* and homomeric α7 are two major nAChR subtypes which have been studied in the brain using positron emission tomography (PET). Our comparative autoradiographic studies of the two receptor types in the mouse and rat brains show major differences in the thalamus (α4β2* >> α7), hippocampus (α7 >> α4β2*), and subiculum (α4β2* >> α7). A relatively newer heteromeric α7β2 nAChR subtype has been identified in the brain which may have a greater role in neurodegeneration. We report the development of KS7 (3-(2-(S)-azetidinylmethoxy)-5-(1,4-diaza-bicyclo[3.2.2]nonane)pyridine) which incorporates structural features of Nifzetidine (high affinity for α4β2* nAChR) and ASEM (high affinity for α7 nAChR) in an effort to target α7 and β2 subunits in α7β2 nAChR. KS7 exhibited higher affinities (IC50 = 50 to 172 nM) for [3H]cytisine radiolabeled sites and weaker affinities (IC50 = 10 μM) for [125I]-α-bungarotoxin radiolabeled rat brain sites in several brain regions. The weaker affinity of KS7 to α7 nAChR may suggest lack of binding at the α7 subunit of α7β2 nAChR. A radiolabeled derivative of KS7 may be required to identify any specific binding to brain regions suggested to contain α7β2 nAChR.

A compact device model along with simulations and an experimental analysis of a forward-biased PN junction-based silicon Mach-Zehnder modulator (MZM) with a phase-shifter length of 0.5 mm is presented. By placing the PN junction to a certain off-center such that 72% of the waveguide is p-doped, the refractive index swing at a given drive voltage swing is increased by 2% compared to the symmetric layout. The effects of the phase shifters’ length mismatch and asymmetric splitting on the modulation efficiency and extinction ratio of the modulator are simulated and compared with experimental results. Without any pre-emphasis or post-processing, a high-speed operation up to 15 Gb/s using a non-return-to-zero modulation format is demonstrated. A modulation efficiency (${{\boldsymbol{V}}_{\boldsymbol{\pi}}}{\boldsymbol{L}}$) as low as 0.07 V × cm is verified and power consumption of 0.88 mW/Gb/s is recorded while a high extinction ratio of 33 dB is experimentally demonstrated. Compared to previously reported forward-biased silicon integrated modulators, without active tuning of the power splitting ratio between the arms, the extinction ratio is 10 dB higher. This MZM along with its compact structure is also sufficiently energy-efficient due to its low power consumption. Thus, it can be suitable for applications like analog signal processing and high-order amplitude modulation transmissions.

The growing demand for bandwidth and energy efficiency requires new solutions for signal detection and processing. We demonstrate a concept for high-bandwidth signal detection with low-speed photodetectors and electronics. The method is based on the parallel optical sampling of a high-bandwidth signal with sinc-pulse sequences provided by a Mach-Zehnder modulator. For the electronic detection and processing this parallel sampling enables to divide the high-bandwidth optical signal with the bandwidth $B$ into $N$ electrical signals with the baseband bandwidth of $B/(\text{2}\,N)$. In proof-of-concept experiments with $N=3$, we present the detection of 24 GHz optical signals by detectors with a bandwidth of only 4 GHz. For ideal components, the sampling and bandwidth down-conversion does not add an excess error to the signals and even for the non-ideal components of our proof-of-concept setup, it is below 1%. Thus, the rms error for the measurement of the 24 GHz signal was reduced by a factor of about 3.4 and the effective number of bits were increased by 1.8.

Sampling is the primary functional step of an analogue to digital conversion, required for sensing, measurement, signal processing, metrology, and various data communication applications. Here we present, for the first time, to the best of our knowledge, the optical sampling of different microwave signals with sinc-pulse sequences with a very compact integrated silicon photonics ring modulator. By a simple time interleaving with three branches, the employed ring modulator enables ultra-compact photonic integrated analog to digital converters with a sampling rate of three times the RF bandwidth of itself and of the used photodetector and electronic devices. Therefore, its analogue bandwidth is 50% higher than the RF bandwidth of the incorporated electronics and photonics. Thus, the method might enable high-bandwidth analogue to digital converters with ultra-compact footprint and lower power consumption for future communication systems, sensors, and measurement devices.

To cope with the exponential increase in internet services and corresponding data traffic, especially data centers and access networks require new high data rate transmission methods with low cost, very small package and low energy consumption. In this paper, we demonstrate a filterless, agnostic Nyquist wavelength division multiplexing (ANy-WDM) transmission system based on cascaded ring modulators and a comb source. The single ring modulator acts as a filter, filtering one of the $n$ WDM lines, generated by the comb. The same ring modulator modulates $k$ time division multiplexed (TDM) channels on the single wavelength. Since each WDM channel, consisting of $k$ time domain channels, has a rectangular bandwidth, the aggregated symbol rate of the superchannel modulated by this system corresponds to the optical bandwidth of all $n$ WDM channels together. The approach is very simple and compact. Since no optical filters, delay lines or other special photonics or high bandwidth electronics is needed, an integration into any photonics platform is straightforward. Thus, the proposed method might enable very compact, ultra-high data rate transmission devices for future data centers and access networks.

Abstract The major losses that limit the efficiency of a single-junction solar cell are thermalization loss and transmission loss. Thus, to efficiently utilize the full solar spectrum and to mitigate these losses, tandem solar cells (TSC) have significantly impacted the photovoltaic (PV) landscape. In this context, the research on perovskite/silicon tandems is currently dominating the research community. The stability improvements of perovskite materials and mature fabrication techniques of silicon have underpinned the rapid progress of perovskite/silicon TSC. However, the low absorption coefficient and high module cost of the silicon are the tailbacks for the mass production of perovskite/silicon TSCs. Therefore, PV technology demands to explore some new materials other than Si to be used as absorber layer in the bottom cell. Thus, here in this work, to mitigate the aforementioned losses and to reduce cost, a 23.36% efficient two-terminal perovskite-PbS CQD monolithic tandem solar cell has been designed through comprehensive device simulations. Before analyzing the performance of the proposed TSC, the performance of perovskite top cells has been optimized in terms of variation in optical properties, thickness, and interface defect density under standalone conditions. Thereafter, filtered spectrum and associated integrated filtered power by the top cell at different perovskite thickness from 50 to 500 nm is obtained to conceive the presence of the top cell above the bottom cell with different perovskite thickness. The current matching by concurrently varying the thickness of both the top and bottom subcell has also been done to obtain the maximum deliverable tandem JSC for the device under consideration. The top/bottom subcell with current matched JSC of 16.68 mA cm−2/16.62 mA cm−2 showed the conversion efficiency of 14.60%/9.07% under tandem configuration with an optimized thickness of 143 nm/470 nm, where the top cell is simulated under AM1.5G spectrum, and bottom cell is exposed to the spectrum filtered by 143 nm thick top cell. Further, the voltages at equal current points are added together to generate tandem J–V characteristics. This work concludes a 23.36% efficient perovskite-PbS CQD tandem design with 1.79 V (VOC), 16.67 mA cm−2 (JSC) and 78.3% (FF). The perovskite-PbS CQD tandem device proposed in this work may pave the way for the development of high-efficiency tandem solar cells for low-cost applications.

The conjecture of stock exchange is the demonstration of attempting to decide the forecast estimation of a particular sector or the market, or the market as a whole. Every stock every investor needs to foresee the future evaluation of stocks, so a predicted forecast of a stock’s future cost could return enormous benefit. To increase the accuracy of the Conjecture of stock Exchange with daily changes in the market value is a bottleneck task. The existing stock market prediction focused on forecasting the regular stock market by using various machine learning algorithms and in-depth methodologies. The proposed work we have implemented describes the new NN model with the help of different learning techniques like hyperparameter tuning which includes batch normalization and fitting it with the help of random-search-cv. The prediction of the Stock exchange is an active area for research and completion in Numerai. The Numerai is the most robust data science competition for stock market prediction. Numerai provides weekly new datasets to mold the most exceptional prediction model. The dataset has 310 features, and the entries are more than 100000 per week. Our proposed new neural network model gives accuracy is closely 86%. The critical point, it isn’t easy with our proposed model with existing models because we are training and testing the proposed model with a new unlabeled dataset every week. Our ultimate aim for participating in Numerai competition is to suggest a neural network methodology to forecast the stock exchange independent of datasets with reasonable accuracy.

Osteoblastoma, a rare osteoblastic tumor, constitutes approximately 1% of all primary bone tumors. It is characterized by osteoid and bone formation with the presence of numerous osteoblasts. A 24-year-old female presented with a chief complaint of a painless swelling beneath the mandible, which was growing during the past 3 years. Radiological picture disclosed a well-circumscribed lesion with patchy radiopaque internal structure. After complete excision, the histopathological diagnosis was a benign osteoblastoma of the mandible. Differential diagnosis and immunohistochemical features are potentially useful for refining diagnosis of osteoblastoma.

Introduction: Cervical cancer is the most common cause of cancer in India. It is considered a preventable disease by WHO because it can be diagnosed in its precancerous stage. But in India women come too late when the cancer is incurable and no treatment is available. However mass screening is not feasible in resource poor settings as it is expensive. But opportunistic screening and downstaging can go a long way in controlling the disease. Objective: To evaluate causative factors and stage of cancer so as to assess strategies to control the disease. Materials and Methods: One year retrospective analysis of cases of carcinoma cervix was done to evaluate incidence, parity, rural/urban, sexual and reproductive factors, socioeconomic factors, contraceptive usage, and disease stage. Results: Total number of gynae admissions was 175 out of which 39(22.28%) cases were of Ca cervix. Most cases (25.64 %) were in 60-64 years age group, followed by 35-39 years (20.51%). Majority (51.28%) were para four and above. Maximum cases (84.61%) belonged to rural background. Discharge per vaginum with pain lower abdomen was commonest presenting symptom (58.97%) followed by postcoital bleeding and irregular bleeding (41.03%). Median age at first sexual contact was 18.9 years. No history of contraceptive usage in 53.84%. Three cases were HIV positive. No patient had screening for cervical cancer. 18(46.15%) cases were of advanced stage, 15(38.46%) stage II and 6(15.38%) to stage I. Conclusion: Main factors responsible were early onset of coitus, absence of contraceptive use, multiparity, poor socioeconomic status, rural background and no cervical cancer screening. In India, women come too late when the cancer is incurable. As mass screening is not feasible in poor resource settings, opportunistic screening and downstaging can go a long way in controlling the disease.

Trauma may lead to fractured teeth with exposed canals in growing children. Some people have a habit of placing foreign objects to remove food plugs from the teeth. These foreign objects may act as a potential source of infection and may later lead to a painful condition. The presence of foreign object in the root canal is one of the challenging occurrences in endodontic therapy. The chance of these foreign objects getting impacted into the tooth is more when pulp chamber is open either because of traumatic injury or large carious exposure. A detailed case history, clinical, and radiographic examinations are required to ascertain the size, position, and likely composition of the object, and also the difficulty involved in its retrieval. This case report describes a self-introduced unusual foreign body and its retrieval from the root canal of upper central incisor by simple orthograde nonsurgical technique.

Introduction: This article seeks to explore tacit knowledge in the context of the practice and the role of a dental educator in a workplace learning environment. Material and Methods: The key theoretical ideologies which underpin the definition of tacit knowledge have been outlined and practical examples to enable conceptualisation. The role tacit knowledge plays in procedural knowledge, performance of a skill and diagnosis and decision‐making has been explained in further detail. Approaches to maximise the educational output of learning opportunities by using tacit knowledge and how an awareness of tacit knowledge can complement reflection have been considered. Results: It is acknowledged that workplace learning is of mutual benefit to the dental educator, trainee and clinical team and that the development of the educator to make tacit knowledge explicit, can be achieved through peer observation, amongst other methods. Conclusion: Tacit knowledge is a key element underpinning learning in the workplace; the use of this knowledge can be applied in an advantageous manner, from both an educational and a personal developmental perspective. [ABSTRACT FROM AUTHOR]