No abstract

As a novel coronavirus continues to emerge throughout China and threaten the globe, its transmission characteristics remain uncertain. Here, we analyze the serial . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not peer-reviewed)The copyright holder for this preprint . https://doi.org/10. 1101 intervals-the time period between the onset of symptoms in an index (infector) case and the onset of symptoms in a secondary (infectee) case-of 468 infector-infectee pairs with confirmed COVID-19 cases reported by health departments in 18 Chinese provinces between January 21, 2020, and February 8, 2020. The reported serial intervals range from -11 days to 20 days, with a mean of 3.96 days (95% confidence interval: 3.53-4.39), a standard deviation of 4.75 days (95% confidence interval: 4.46-5.07), and 12.1% of reports indicating pre-symptomatic transmission.

Background Knowledge on the epidemiological features and transmission patterns of COVID-19 is accumulating. Detailed line-list data with household settings can advance the understanding of COVID-19 transmission dynamics. Methods A unique database with detailed demographic characteristics, travel history, social relationships, and epidemiological timelines for 1,407 transmission pairs that formed 643 transmission clusters in mainland China was reconstructed from 9,120 COVID-19 confirmed cases reported during January 15 - February 29, 2020. Statistical model fittings were used to identify the super-spreaders and estimate serial interval distributions. Age and gender-stratified hazard of infection were estimated for household versus non-household transmissions. Results There were 34 primary cases identified as super-spreaders, with 5 super-spreading events occurred within households. Mean and standard deviation of serial intervals were estimated as 5.0 (95% CrI: 4.4, 5.5) and 5.2 (95% CrI: 4.9, 5.7) days for household transmissions and 5.2 (95% CrI: 4.6, 5.8) and 5.3 (95% CrI: 4.9, 5.7) days for non-household transmissions, respectively. Hazard of being infected outside of households is higher for age between 18 and 64 years, whereas hazard of being infected within households is higher for young and old people. Conclusions Non-negligible frequency of super-spreading events, short serial intervals, and a higher risk of being infected outside of households for male people of working age indicate a significant barrier to the identification and management of COVID-19 cases, which requires enhanced non-pharmaceutical interventions to mitigate this pandemic.

Ionotropic ␣-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors (iGluRs) mediate the majority of excitatory synaptic transmission in the CNS and are essential for the induction and maintenance of long-term potentiation and long-term depression, two cellular models of learning and memory. We identified a genomic deletion (0.4 Mb) involving the entire GRIA3 (encoding iGluR3) by using an X-array comparative genomic hybridization (CGH) and four missense variants (G833R, M706T, R631S, and R450Q) in functional domains of iGluR3 by sequencing 400 males with X-linked mental retardation (XLMR). Three variants were found in males with moderate MR and were absent in 500 control males. Expression studies in HEK293 cells showed that G833R resulted in a 78% reduction of iGluR3 due to protein misfolding. Whole-cell recording studies of iGluR3 homomers in HEK293 cells revealed that neither iGluR3-M706T (S2 domain) nor iGluR3-R631S (near channel core) had substantial channel function, whereas R450Q (S1 domain) was associated with accelerated receptor desensitization. When forming heteromeric receptors with iGluR2 in HEK293 cells, all four iGluR3 variants had altered desensitization kinetics. Our study provides the genetic and functional evidence that mutant iGluR3 with altered kinetic properties is associated with moderate cognitive impairment in humans.glutamate receptor ͉ X-linked mental retardation

Black phosphorus (BP) has recently attracted significant attention due to its exceptional physical properties. Currently, high-quality few-layer and thin-film BP are produced primarily by mechanical exfoliation, limiting their potential in future applications. Here, the synthesis of highly crystalline thin-film BP on 5 mm sapphire substrates by conversion from red to black phosphorus at 700 °C and 1.5 GPa is demonstrated. The synthesized ≈50 nm thick BP thin films are polycrystalline with a crystal domain size ranging from 40 to 70 µm long, as indicated by Raman mapping and infrared extinction spectroscopy. At room temperature, field-effect mobility of the synthesized BP thin film is found to be around 160 cm V s along armchair direction and reaches up to about 200 cm V s at around 90 K. Moreover, red phosphorus (RP) covered by exfoliated hexagonal boron nitride (hBN) before conversion shows atomically sharp hBN/BP interface and perfectly layered BP after the conversion. This demonstration represents a critical step toward the future realization of large scale, high-quality BP devices and circuits.