Spectrally efficient multi-service fiber-wireless access in low-cost direct-detection THz system at 300†GHz.

This Letter demonstrates a novel, to the best of knowledge, overlapping single-sideband (OSSB) transmission scheme for spectrally efficient multi-service fiber-wireless (FiWi) access in a low-cost direct-detection (DD) THz system. Utilizing the proposed OSSB scheme, user data from different services can share the same spectrum resource yet can be successfully demodulated via one cost-effective DD THz receiver in conjunction with the Kramers-Kronig (KK) based SSB field reconstruction and look-up table (LUT) enabled signal separation algorithms. A proof-of-principle experiment is conducted. Based on an IQ modulator and a single THz zero-bias diode (ZBD), two independent 10-GBd quadrature phase shift keying (QPSK) signals with an overlapped spectrum are successfully demodulated after 20-km fiber and up to 3-m wireless transmission at the 300-GHz band. To the best of our knowledge, this is the first demonstration of multi-service FiWi access with an OSSB format in a 300-GHz DD THz system.

Multi-objective Bayesian algorithm automatically discovers low-cost high-growth serum-free media for cellular agriculture application.

In this work, we applied a multi-information source modeling technique to solve a multi-objective Bayesian optimization problem involving the simultaneous minimization of cost and maximization of growth for serum-free C2C12 cells using a hyper-volume improvement acquisition function. In sequential batches of custom media experiments designed using our Bayesian criteria, collected using multiple assays targeting different cellular growth dynamics, the algorithm learned to identify the trade-off relationship between long-term growth and cost. We were able to identify several media with >100% more growth of C2C12 cells than the control, as well as a medium with 23% more growth at only 62.5% of the cost of the control. These algorithmically generated media also maintained growth far past the study period, indicating the modeling approach approximates the cell growth well from an extremely limited data set.

Alike but also different: a spatiotemporal analysis of the older populations in Zhejiang and Jilin provinces, China.

According to the 7th National Population Census, China is experiencing rapid growth of its ageing population, with large spatial disparities in the distribution of older folks in different regions. And yet, scant comparative research has been conducted on the two regions of Zhejiang and Jilin in particular, which differ considerably in economic development but witness nearly the same ageing trend. In response, this article compares Zhejiang, an advanced economic province, with Jilin, with its relatively low level of economic development, to explore the ageing issue and analyse the spatial correlation between older populations and socioeconomic factors. Using the spatiotemporal data analysis and geographical detector approaches, we obtain three significant findings: 1. both provinces have maintained steady rates of increase in ageing; 2. the older populations in Zhejiang and Jilin are mostly concentrated in the provincial capitals and nearby cities with reasonably established economies; and 3. the factors, including local fiscal expenditures, beds in hospitals and nursing homes, and coverage of social security, show a highly similar spatial pattern between older populations in Zhejiang and Jilin. The q-values of all the selected socioeconomic factors in Jilin showed a growth trend, indicating that the spatial correlation between these factors and ageing is strengthening year on year, that is, the resources gained from the socioeconomic development of Jilin have shifted steadily toward old-age services. As a consequence, a vicious circle of the slowing down of the economic growth drives away working forces and quickens the pace of population ageing, is present. From a policy perspective, Jilin province is strongly dependent on state-owned enterprises characterised by institutional rigidity, an inflexible market economy and an under-developed private sector, all of which are profoundly influenced by ageing. The consequence is large population outflows of young people. In contrast, the economy of Zhejiang province is partially decoupled from the ageing trend, so the gap in level of development between its counties has been narrowing. The policy implication here is that Zhejiang represents an active private economy that has coped successfully with ageing by attracting young migrants and developing new forms of development, such as the digital economy.

Accuracy assessment of land cover products in China from 2000 to 2020.

The accuracy assessment of land cover data is of significant value to accurately monitor and objectively reproduce spatio-temporal dynamic changes to land surface landscapes. In this study, the interpretation and applicability of CCI, MCD, and CGLS long time-series land cover data products for China were evaluated via consistency analysis and a confusion matrix system using NLUD-C periodic products as reference data. The results showed that CGLS had the highest overall accuracy, Kappa coefficient, and area consistency in the continuous time-series evaluation, followed by MCD, whereas CCI had the worst performance. For the accuracy assessment of subdivided land cover types, the three products could accurately describe the distribution of forest land in China with a high recognition level, but their recognition ability for water body and construction land was poor. Among the other types, CCI could better identify cropland, MCD for grassland, and CGLS for unused land. Based on these evaluation results and characteristics of the data products, we developed suitable selection schemes for users with different requirements.

The mechanism of the irradiation synergistic effect of silicon bipolar junction transistors explained by multiscale simulations of Monte Carlo and excited-state first-principle calculations.

Neutron and γ-ray irradiation damages to transistors are found to be non-additive, and this is denoted as the irradiation synergistic effect (ISE). Its mechanism is not well-understood. The recent defect-based model [Song and Wei, ACS Appl. Electron. Mater. 2, 3783 (2020)] for silicon bipolar junction transistors (BJTs) achieves quantitative agreement with experiments, but its assumptions on the defect reactions are unverified. Going beyond the model requires directly representing the effect of γ-ray irradiation in first-principles calculations, which was not feasible previously. In this work, we examine the defect-based model of the ISE by developing a multiscale method for the simulation of the γ-ray irradiation, where the γ-ray-induced electronic excitations are treated explicitly in excited-state first-principles calculations. We find the calculations agree with experiments, and the effect of the γ-ray-induced excitation is significantly different from the effects of defect charge state and temperature. We propose a diffusion-based qualitative explanation of the mechanism of positive/negative ISE in NPN/PNP BJTs in the end.

Exploring racial and gender disparities in voice biometrics.

Systemic inequity in biometrics systems based on racial and gender disparities has received a lot of attention recently. These disparities have been explored in existing biometrics systems such as facial biometrics (identifying individuals based on facial attributes). However, such ethical issues remain largely unexplored in voice biometric systems that are very popular and extensively used globally. Using a corpus of non-speech voice records featuring a diverse group of 300 speakers by race (75 each from White, Black, Asian, and Latinx subgroups) and gender (150 each from female and male subgroups), we explore and reveal that racial subgroup has a similar voice characteristic and gender subgroup has a significant different voice characteristic. Moreover, non-negligible racial and gender disparities exist in speaker identification accuracy by analyzing the performance of one commercial product and five research products. The average accuracy for Latinxs can be 12% lower than Whites (p < 0.05, 95% CI 1.58%, 14.15%) and can be significantly higher for female speakers than males (3.67% higher, p < 0.05, 95% CI 1.23%, 11.57%). We further discover that racial disparities primarily result from the neural network-based feature extraction within the voice biometric product and gender disparities primarily due to both voice inherent characteristic difference and neural network-based feature extraction. Finally, we point out strategies (e.g., feature extraction optimization) to incorporate fairness and inclusive consideration in biometrics technology.

[Risk prediction for deep venous thrombosis after total knee arthroplasty based on modified Caprini risk assessment model:a confirmatory study].

OBJECTIVE: To investigate the effectiveness of modified Caprini risk assessment model(Caprini MRAM) in predicting the risk of deep venous thrombosis (DVT) after total knee arthroplasty (TKA). METHODS: A case-control study was used to collect 43 patients with DVT after TKA in lower limb department of Sichuan Orthopedic Hospital from January 2016 to November 2020 in the positive group, and 172 patients without DVT after TKA in the same period according to the 1∶4 ratio between positive and control group were selected in the control group. Caprini MRAM was used to score and grade the risk of DVT. The clinical data, score and risk classification of the two groups were compared. The relationship between the risk of DVT in the patients after TKA and the risk factors in the risk ckassification and assessment of Caprini MRAM was analyzed by multivariate logistic regression model. RESULTS: The average score of caprini in DVT group was significantly higher than that in control group[(8.11±2.91) vs(4.07±2.12), P<0.001];DVT group was mainly at medium and high risk group(66.67%), while the control group was mainly at low risk (77.33%). There was a significant difference between the two groups in risk classification composition (P<0.001). BMI≥30 kg/m2, lower extremity edema (<1 month), severe pulmonary disease (<1 month), acute myocardial infarction (<1 month), bed rest (> 2 h), history of superficial or deep vein or pulmonary embolism and family history of thrombosis were the main risk factors for DVT in patients after TKA(all P<0.05). Preoperative D-dimer elevation (OR=4.380), BMI≥30 kg/m2(OR=2.518), lower extremity edema(<1 month)(OR=7.652), acute myocardial infarction (<1 month) (OR=1.994), bed rest (> 72 h)(OR=3.897), history of superficial or deep vein or pulmonary embolism (OR=13.517) and family history of blood embolism (OR=6.551) were independent risk factors for DVT in patients after TKA (all P<0.05). The risk of DVT was 13.457 and 2.739 times higher in high and moderate risk TKA patients with Caprini MRAM classification, respectively. CONCLUSION: Caprini MRAM can be used to predict the risk of DVT in patients after TKA, especially for patients with high risk.

Biogranulation process facilitates cost-efficient resources recovery from microalgae-based wastewater treatment systems and the creation of a circular bioeconomy.

Energy self-sufficient wastewater treatment designs can reduce net energy consumption and achieve resources recovery. Microalgae are regarded as a promising candidate for developing a circular bioeconomy in wastewater treatment plants (WWTPs) due to its potential for simultaneous wastewater remediation and high value-added materials production. Much effort has been made to overcome the high production costs for microalgae; however, biomass harvesting still remains as the bottleneck for its large-scale application. In this study, the novel biogranulation system facilitating easier and faster microalgae harvesting was firstly compared with the conventional suspended culture for energy-efficiency and sustainability assessment on microalgae (Ankistrodesmus falcatus var. acicularis) cultivation using the synthetic anaerobic digestion liquor. Results demonstrated that the biogranulation system enhanced volumetric biomass productivity (223.17 ± 11.82 g/m3/day) by about 4.4 times compared to that from the suspended system (41.57 ± 2.08 g/m3/day) under the same environmental conditions. It was noticed that lipids, carbohydrates and proteins were accumulated in microalgae cells along with nutrients remediation, and the microalgae granules with much higher proteins content (313.28 ± 26.67 mg/g-VSS) could be easily harvested through 2 min gravity sedimentation with little impact on the contents of carbohydrates and lipids. In the whole cultivation and harvesting process, the biomass mass-based electricity consumption and footprint demand by the biogranulation system were reduced by 58% and 76%, respectively. Results from this study provide a cost-effective and sustainable approach for microalgae in the treatment of nutrients rich digestion liquor with simultaneous production of valuable biomaterials.

A model mismatch assessment method of MPC by decussation.

For the model plant mismatch (MPM) assessment of MPC systems, a correlation analysis method between the input and the disturbance (CAID) is proposed and is combined with model quality index (MQI) for its application in multivariable system. By deducing the input-output correlation coefficient variation law of adding independent variables in a function, the paper defines the CAID index of assessing the MPM. To realize the exact location of sub-model mismatch in multivariable system, the synthetical disturbance variable is constructed through principle component analysis (PCA), then it is used to define the synthetical CAID index of multivariable MPC system, and finally the decussation method combining synthetical CAID and MQI is presented. The proposed method is validated in Wood-Berry distillation process and an industrial air separate process.

Adaptive landscape flattening in amino acid sequence space for the computational design of protein:peptide binding.

For the high throughput design of protein:peptide binding, one must explore a vast space of amino acid sequences in search of low binding free energies. This complex problem is usually addressed with either simple heuristic scoring or expensive sequence enumeration schemes. Far more efficient than enumeration is a recent Monte Carlo approach that adaptively flattens the energy landscape in sequence space of the unbound peptide and provides formally exact binding free energy differences. The method allows the binding free energy to be used directly as the design criterion. We propose several improvements that allow still more efficient sampling and can address larger design problems. They include the use of Replica Exchange Monte Carlo and landscape flattening for both the unbound and bound peptides. We used the method to design peptides that bind to the PDZ domain of the Tiam1 signaling protein and could serve as inhibitors of its activity. Four peptide positions were allowed to mutate freely. Almost 75 000 peptide variants were processed in two simulations of 109 steps each that used 1 CPU hour on a desktop machine. 96% of the theoretical sequence space was sampled. The relative binding free energies agreed qualitatively with values from experiment. The sampled sequences agreed qualitatively with an experimental library of Tiam1-binding peptides. The main assumption limiting accuracy is the fixed backbone approximation, which could be alleviated in future work by using increased computational resources and multi-backbone designs.

Computational Design of the Tiam1 PDZ Domain and Its Ligand Binding.

PDZ domains direct protein-protein interactions and serve as models for protein design. Here, we optimized a protein design energy function for the Tiam1 and Cask PDZ domains that combines a molecular mechanics energy, Generalized Born solvent, and an empirical unfolded state model. Designed sequences were recognized as PDZ domains by the Superfamily fold recognition tool and had similarity scores comparable to natural PDZ sequences. The optimized model was used to redesign the two PDZ domains, by gradually varying the chemical potential of hydrophobic amino acids; the tendency of each position to lose or gain a hydrophobic character represents a novel hydrophobicity index. We also redesigned four positions in the Tiam1 PDZ domain involved in peptide binding specificity. The calculated affinity differences between designed variants reproduced experimental data and suggest substitutions with altered specificities.