Booster vaccination protection against SARS-CoV-2 infections in young adults during an Omicron BA.1-predominant period: A retrospective cohort study.

BACKGROUND: While booster vaccinations clearly reduce the risk of severe Coronavirus Disease 2019 (COVID-19) and death, the impact of boosters on Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infections has not been fully characterized: Doing so requires understanding their impact on asymptomatic and mildly symptomatic infections that often go unreported but nevertheless play an important role in spreading SARS-CoV-2. We sought to estimate the impact of COVID-19 booster doses on SARS-CoV-2 infections in a vaccinated population of young adults during an Omicron BA.1-predominant period. METHODS AND FINDINGS: We implemented a cohort study of young adults in a college environment (Cornell University's Ithaca campus) from a period when Omicron BA.1 was the predominant SARS-CoV-2 variant on campus (December 5 to December 31, 2021). Participants included 15,800 university students who completed initial vaccination series with vaccines approved by the World Health Organization for emergency use, were enrolled in mandatory at-least-weekly surveillance polymerase chain reaction (PCR) testing, and had no positive SARS-CoV-2 PCR test within 90 days before the start of the study period. Robust multivariable Poisson regression with the main outcome of a positive SARS-CoV-2 PCR test was performed to compare those who completed their initial vaccination series and a booster dose to those without a booster dose. A total of 1,926 unique SARS-CoV-2 infections were identified in the study population. Controlling for sex, student group membership, date of completion of initial vaccination series, initial vaccine type, and temporal effect during the study period, our analysis estimates that receiving a booster dose further reduces the rate of having a PCR-detected SARS-CoV-2 infection relative to an initial vaccination series by 56% (95% confidence interval [42%, 67%], P < 0.001). While most individuals had recent booster administration before or during the study period (a limitation of our study), this result is robust to the assumed delay over which a booster dose becomes effective (varied from 1 day to 14 days). The mandatory active surveillance approach used in this study, under which 86% of the person-days in the study occurred, reduces the likelihood of outcome misclassification. Key limitations of our methodology are that we did not have an a priori protocol or statistical analysis plan because the analysis was initially done for institutional research purposes, and some analysis choices were made after observing the data. CONCLUSIONS: We observed that boosters are effective, relative to completion of initial vaccination series, in further reducing the rate of SARS-CoV-2 infections in a college student population during a period when Omicron BA.1 was predominant; booster vaccinations for this age group may play an important role in reducing incidence of COVID-19.

Modeling for COVID-19 college reopening decisions: Cornell, a case study.

We consider epidemiological modeling for the design of COVID-19 interventions in university populations, which have seen significant outbreaks during the pandemic. A central challenge is sensitivity of predictions to input parameters coupled with uncertainty about these parameters. Nearly 2 y into the pandemic, parameter uncertainty remains because of changes in vaccination efficacy, viral variants, and mask mandates, and because universities' unique characteristics hinder translation from the general population: a high fraction of young people, who have higher rates of asymptomatic infection and social contact, as well as an enhanced ability to implement behavioral and testing interventions. We describe an epidemiological model that formed the basis for Cornell University's decision to reopen for in-person instruction in fall 2020 and supported the design of an asymptomatic screening program instituted concurrently to prevent viral spread. We demonstrate how the structure of these decisions allowed risk to be minimized despite parameter uncertainty leading to an inability to make accurate point estimates and how this generalizes to other university settings. We find that once-per-week asymptomatic screening of vaccinated undergraduate students provides substantial value against the Delta variant, even if all students are vaccinated, and that more targeted testing of the most social vaccinated students provides further value.

Analysis and Design of a Non-Magnetic Bulk CMOS Passive Circulator Using 25% Duty-Cycle Clock.

A circulator, which is a non-reciprocal device, is widely used in full-duplex systems, future communication and sensing networks, and quantum computing, and it is difficult to implement a passive topology on a chip. Based on switch-based spatio-temporal conductivity modulation, in this study, we design and implement a non-magnetic on-chip passive circulator operating at the Ku band in a 90-nm bulk CMOS technology using a 25% duty-cycle I/Q clock signal. With the virtue of the four-phase non-overlapping clock signal, the proposed circulator achieves a 3.9 dB transmitter (TX)-to-antenna (ANT) and a 4.0 dB ANT-to-receiver (RX) insertion loss with a 1-dB bandwidth of 2.7 GHz (21.4%). The TX-to-RX isolation is better than 17.2 dB, and the TX-to-ANT IIP3 and ANT-to-RX IIP3 are 19.7 dBm and 20.0 dBm, respectively, while occupying a die area of 1.55 mm × 1.15 mm. Although low-cost bulk CMOS technology is used, competitive isolation, linearity performance, and isolation bandwidth are achieved in the proposed design.

[Screening of tomato cultivars in cadmium-polluted areas and study on their antioxidant capacity].

To screen the available tomato pollution-safe cultivar varieties and reduce the potential food safety risks in Cd-polluted areas, the differences of Cd accumulation in different tomato (Solanum lycopersicum) varieties in southern China were studied by soil culture and hydroponic experiments. Firstly, the high and low accumulation varieties were selected from 25 tomato varieties under 2.94 mg/kg Cd stress by soil culture test, and then the responses of high and low accumulation tomato varieties to Cd stress were determined by hydroponic experiments. The results of soil culture test show that under 2.94 mg/kg Cd stress, there were significant differences in plant height, total biomass and yield among 25 tomato cultivars, and the Cd contents of fruits of all 25 tomato cultivars exceeded the highest limit value (0.05 mg/kg) of CAC (Codex alimentarius commission). Through cluster analysis, 7, 4 and 14 varieties accumulating relatively high, medium, and low concentrations of Cd in the fruits were screened, among which the highest, the lowest, and the average Cd contents in the fruits were 3.06 mg/kg DW, 1.47 mg/kg DW, and 2.21 mg/kg DW, respectively. The results of hydroponic experiment show that under the same concentration of Cd stress, Qiantangxuri F1, a high Cd accumulating variety, absorbed Cd faster, accumulated more Cd, used shorter oxidative stress response time and had stronger tolerance to Cd than Zhefen 3053, a low Cd accumulating variety. The typical high and low Cd accumulating varieties can provide a reference for agricultural production in heavy metal polluted areas and the development of molecular-assisted breeding methods of PSC. At present, cultivating low Cd accumulating PSC varieties and dynamic monitoring of Cd contents in tomato fruits are feasible methods in medium and light Cd-polluted areas.

[Effects of Kochia scoparia-Brassica rapa rotation on Cd uptake by Brassica rapa].

In this study, pot and field experiments were conducted to study the enrichment of soil cadmium by Kochia scoparia. Further, rotations in pot experiments were carried out with four varieties of Brassica rapa to verify the remediation effect of Kochia scoparia on cadmium contamination in soil. The enrichment capacity of Kochia scoparia was leaf > root > stem with bioconcentration factors (BCFCd) of 15.07, 5.44 and 2.96, respectively. The total cadmium in soil decreased by 6.02% to 13.60% after planting Kochia scoparia, and the activities of soil urease and acid phosphatase also increased. The results of pot cultivation shows that the above-ground cadmium content of Brassica rapa in Kochia scoparia-Brassica rapa rotation system decreased by 17.21% on average compared with the control group without rotation, whereas the biomass increased slightly, and the above-ground translocation factors (TFCd) did not change significantly. These results suggest that the rotation of Brassica rapa with Kochia scoparia could increase the yield of Brassica rapa, and effectively reduce the cadmium content in edible parts of Brassica rapa, toward the purpose of realizing the green agricultural concept of "harnessing while producing".

[Effects of intercropping on cadmium uptake by maize and tomato].

In order to explore the effect of intercropping on the uptake of heavy metal cadmium (Cd), pot experiments were undertaken using three different planting methods: monoculture, restrictive intercropping and intercropping. The effects of Cd accumulation in different plant parts, and their causes, were examined using a plant species regarded as a relatively high heavy metal accumulator (tomato: Lycopersicon esculentum var. Zhongshu 4) and a species regarded as a relatively low heavy metal accumulator (maize: Zea mays L. var. Jinzhumi). Cd levels for all experiments were 3.70 mg/kg. Results indicate that restricted intercropping and intercropping of tomato and maize increased the accumulation of Cd (from 13.52 mg/kg to 24.94 mg/kg and 27.30 mg/kg in tomato leaf, respectively). Compared with the control group, pH levels in soil surrounding tomato roots in the intercropped samples decreased and the activity of acid phosphatase increased, while the activity of urease decreased. Intercropping can also change the structure of the crop root microorganism population, increase the abundance of microbiological species that promote the uptake of heavy metals, and finally achieve high accumulation of Cd in tomatoes. Our research results provide reference for controlling soil heavy metal pollution and ensuring food safety by using an intercropping model.

Soil cadmium extraction in Chinese cabbage and cabbage intercropping / Extração de cádmio no solo em repolho chinês e consorciação de repolho

ABSTRACT: Toxic metals contamination of soil has become a serious problem in recent years. In this study, Chinese cabbage (a relatively high-accumulator of cadmium (Cd)) and cabbage (a relatively low-accumulator of Cd) were cultured in monoculture and in intercropping in the Cd-contaminated soil, to evaluate the effect of intercropping on the alteration of Cd extraction. Both the pot experiments and field experiments indicated that intercropping increased the Cd extraction by Chinese cabbage and decreased the Cd extraction by cabbage. Thus, Cd extraction was advanced while safe production was obtained. Further pot experiment was conducted to investigate the alterations of soil Cd fractions, soil pH, and soil enzyme activities to reveal their possible relationship with Cd extraction between different planting patterns. Results revealed that three individual Chinese cabbages in one intercropping pot played the same effect on alteration of these factors as six individual Chinese cabbages in one monoculture pot. The intercropping increased Cd extraction by Chinese cabbage and decreased Cd extraction by cabbage, probably by influencing mechanisms such as soil enzyme activities (especially the urease activity) in the cultivation system. Effect of intercropping on Cd accumulation is an important issue in cultivation of vegetables in potentially contaminated land.

RESUMO: A contaminação do solo por metais tóxicos tornou-se um problema grave nos últimos anos. Neste estudo, dois tipos de repolhos, o repolho chinês (maior acumulador de cádmio (Cd)) e o repolho comum (menor acumulador de Cd) foram cultivados em monocultivo e em consórcio, em solo contaminado com esse metal, para avaliar o efeito do consórcio na extração de Cd do solo. Os experimentos em vasos de campo indicaram que o consórcio aumentou a extração desse metal pelo repolho chinês e diminuiu a extração pelo repolho comum. Assim, aumentou a extração de Cd do solo, proporcionando segurança alimentar. Outro experimento em vaso foi conduzido para investigar as alterações das frações de Cd do solo, o pH do solo e atividades enzimáticas do solo, para revelar possíveis efeitos na extração desse metal entre os sistemas de plantio. Os resultados do experimento em vaso revelaram que três repolhos da china, em cultivo consorciado, proporcionaram o mesmo efeito nessas variáveis, que os observados com seis plantas desse tipo de repolho, em monocultura. O consórcio influenciou as frações de Cd do solo devido a maior influência das hortaliças no pH do solo e nas atividades enzimáticas (especialmente a urease), resultando maior extração de Cd pelo repolho chinês e menor pelo repolho comum.