Dominant Period Research Articles

Investigation of local soil properties of Erzurum province (Eastern Türkiye) by Horizontal/Vertical Spectral ratio method

Erzurum province is a basin developed under the effect of strike-slip faults in the Eastern Anatolia region. Erzurum province is generally influenced by the left strike-slip Erzurum Fault Zone, the left- strike-slip Aşkale fault, and the Başköy-Kandilli reverse fault. It is also located approximately 80 km from the Karlıova joint, which is the intersection of the North Anatolian and East Anatolian Faults. When the earthquakes of the instrumental and historical periods are analyzed, it is seen that many damaging earthquakes of medium to large magnitude have occurred in Erzurum province. Erzurum basin is generally covered with old alluvium at the edges of the plains, while the flat areas in the central parts are covered with new alluvium. Determination of local soil properties in regions with high earthquake hazard plays an important role in reducing earthquake risks. For this purpose, single station microtremor measurements were applied at 25 sites in Palandöken and Yakutiye districts of Erzurum province. The measurements were taken for at least 30 minutes and evaluated according to the Horizontal/Vertical Spectral Ratio method. As a result of the analysis, the dominant period, H/V ratio and vulnerability index (Kg) values of the measurement points were calculated. The period values obtained vary between 0.15 s and 3.7 s, while the H/V ratios vary between 2.2 and 8.5. The Kg value obtained using these parameters is defined as the vulnerability of the soil. It is concluded that high period, high H/V and high Kg values are obtained in areas with recent alluvium and multidisciplinary analyses should be performed in soil investigations in these regions.

Insight into the seismic response of gravity retaining walls

An extensive study of gravity walls subjected to strong seismic excitation is presented, exploring the role of parameters such as the width of wall, the type of excitation (idealised wavelets or recorded accelerograms), the peak ground acceleration (PGA), the dominant period (TP) of the wavelets, the accelerogram’s polarity and the coefficient of friction of the wall–soil interface. The retaining and foundation soil consists of dry sand layers modeled by a refined constitutive model. Appropriate interface elements, allowing separation and sliding, model the wall–soil interface. Results are presented mainly in terms of time-histories and dimensionless soil pressure distributions. Both horizontal and vertical seismic soil pressures are explored and compared with the classical Mononobe-Okabe–type and Rankine–type pseudostatic analytical solutions. It is shown that reduced acceleration coefficients must be input in such solutions to obtain reasonable results.

Tracking temporal variations of fatality and symptomology correlated with COVID-19 dominant variants and vaccine effectiveness in the United States.

We described how COVID-19 fatality and symptoms varied by dominant variant and vaccination in the US. Using the Restricted Access Dataset from the US CDC (1/1/2020-10/20/2022), we conducted a cross-sectional study assessing differences in COVID-19 deaths, severity indicators (hospitalization, ICU, pneumonia, abnormal X-ray, acute respiratory distress syndrome, mechanical ventilation) and 12 mild symptoms by dominant variant/vaccination periods using logistic regression after controlling for confounders. We found the highest fatality during the dominant periods of Wild (4.6%) and Delta (3.4%). Most severe symptoms appeared when Delta was dominant (Rate range: 2.0-9.4%). Omicron was associated with higher mild symptoms than other variants. Vaccination showed consistent protection against death and severe symptoms for most variants (Risk Ratio range: 0.41-0.93). Boosters, especially the second, provided additional protection, reducing severe symptoms by over 50%. This dataset may serve as a useful tool to monitor temporospatial changes of fatality and symptom for case management and surveillance.

Seasonal habitat use and diel vertical migration in female spurdog in Nordic waters

BackgroundStudying habitat use and vertical movement patterns of individual fish over continuous time and space is innately challenging and has therefore largely remained elusive for a wide range of species. Amongst sharks, this applies particularly to smaller-bodied and less wide-ranging species such as the spurdog (Squalus acanthias Linnaeus, 1758), which, despite its importance for fisheries, has received limited attention in biologging and biotelemetry studies, particularly in the North-East Atlantic.MethodsTo investigate seasonal variations in fine-scale niche use and vertical movement patterns in female spurdog, we used archival data from 19 pregnant individuals that were satellite-tagged for up to 365 days in Norwegian fjords. We estimated the realised niche space with kernel densities and performed continuous wavelet analyses to identify dominant periods in vertical movement. Triaxial acceleration data were used to identify burst events and infer activity patterns.ResultsPregnant females frequently utilised shallow depths down to 300 m at temperatures between 8 and 14 °C. Oscillatory vertical moments revealed persistent diel vertical migration (DVM) patterns, with descents at dawn and ascents at dusk. This strict normal DVM behaviour dominated in winter and spring and was associated with higher levels of activity bursts, while in summer and autumn sharks predominantly selected warm waters above the thermocline with only sporadic dive and bursts events.ConclusionsThe prevalence of normal DVM behaviour in winter months linked with elevated likely foraging-related activity bursts suggests this movement behaviour to be foraging-driven. With lower number of fast starts exhibited in warm waters during the summer and autumn months, habitat use in this season might be rather driven by behavioural thermoregulation, yet other factors may also play a role. Individual and cohort-related variations indicate a complex interplay of movement behaviour and habitat use with the abiotic and biotic environment. Together with ongoing work investigating fine-scale horizontal movement as well as sex- and age-specific differences, this study provides vital information to direct the spatio-temporal distribution of a newly reopened fishery and contributes to an elevated understanding of the movement ecology of spurdog in the North-East Atlantic and beyond.Graphical

Assessing the Impact of Primary-Series Infection and Booster Vaccination on Protection against Omicron in Hong Kong: A Population-Based Observational Study.

This study aimed to assess the real-world effectiveness of vaccines and hybrid immunity in preventing infections during the Omicron prevalent period in Hong Kong. This study analyzed vaccination records and COVID-19 confirmed case records from 1 January 2022 to 28 January 2023 and included a total of 7,165,862 individuals with vaccination or infection records. This study found that an additional vaccine dose offered increased protection against Omicron BA.1/2 and BA.4 infections for individuals without prior infections in general. Hybrid immunity, acquired through vaccination and natural infection, was found to be significantly stronger than that provided by vaccines alone. The Comirnaty Original/Omicron BA.4/5 bivalent vaccine, introduced in December 2022, was associated with a lower risk of BA.4 infection when administered as a booster dose after three doses of CoronaVac. However, individuals with four doses of the CoronaVac vaccine did not exhibit a significantly lower risk of infection compared to those with three doses during the BA.4 dominant period. This study highlights the importance of promoting booster shot uptake and encouraging vaccination among those who have recovered from COVID-19 infections. The potential immune imprinting effect associated with the Comirnaty and CoronaVac vaccine underscores the need for continued surveillance and research to optimize vaccination strategies for emerging variants.

Interpretation of Microtremor Data Through Analysis Horizontal to Vertical Spectral Ratio (HVSR) for Microzonation of Seismic Earthquake Hazards in Baubau City

Research has been carried out on seismic hazard microzonation in the city of Bau – bau using microtremor data. The aim of this research is to determine the seismic vulnerability index based on horizontal to vertical spectral ratio (HVSR) analysis and create a dominant frequency microzonation map (F0), dominant period map (T0), amplification factor map (A0), and seismic vulnerability index map (Kg) from microtremor data which can describe the level of vulnerability of an area to seismic hazards. Microtremor measurements were carried out using a portable three-component seismograph (TDS. 303), the data was analyzed with gepsy software via the HVSR method. The research results show that the distribution of dominant frequency values ​​(F0), ranges from 0.4795 Hz to 16.6383 Hz, dominant period values ​​(T0), ranges from 0.0601 seconds to 2.0854 seconds, amplification factor values ​​(A0), ranges from 1.2285 to 4.9043, and the seismic vulnerability index (Kg) value ranges from 0.1043 to 11.0276. The values ​​(F0), (T0), (A0), and (Kg) are interpreted by referring to literature data and surface geological maps of the research area. The results show that the study area has a small portion of sediment layers that are vulnerable to seismic hazards.

Site-Specific Spectra for the City of Mexicali, Mexico, Obtained from April 2010 Earthquake Records

The April 2010 earthquake (Mw = 7.2), which occurred about 40 km to the southeast of the city of Mexicali, Mexico, caused significant damage to buildings. To improve knowledge of the seismic response of the soil due to the occurrence of earthquakes, a response spectrum at 5% damping was calculated. A comparison between the spectral ordinates obtained in this study and the spectra proposed by the regulations of the Federal Electricity Commission (CFE for its acronym in Spanish) in its seismic design for civil works manual, which is currently used as the design standard throughout the country, was made. We calculated response spectra using records from the April 2010 earthquake and a stratigraphic profile of the city to calculate a transfer function. We first corrected the records for site effect due to stations being over sedimentary soil, and then used them as Green functions to perform a numerical simulation of propagation through the stratigraphic profile to obtain a simulated surface record from which response spectra were calculated. Additionally, ambient seismic noise was measured at the same site to get the dominant period (To). We observed that the transfer function was similar to the spectral quotient up to 5 Hz and that To calculated in both ways gave similar values. The comparison suggests that the design spectrum of the CFE regulation can be considered as a representative spectrum for Mexicali for periods greater than 1.3 s, but not for the zone of short periods.

Geochemistry of Quaternary sediments in the northwestern South China Sea: Sediment provenance and mid-Pleistocene transition

The Quaternary sediments in the northwestern South China Sea (NW-SCS) provide valuable information about provenance, climate and sea level changes. However, the correlation between the geochemical records in marine sediments and these influencing factors remains less understood in the NW-SCS. Two wells penetrated Quaternary sediments on the shelf and shelf margin of the NW-SCS and provide an excellent dataset. In this study, the major, trace, and rare earth elements in the sediments were analyzed to reveal the Quaternary provenance changes that correlate with the climatic Middle Pleistocene transition (MPT). These results indicate that the core sediments were mainly derived from felsic source rocks and the degree of chemical weathering in the source areas is relatively low (CIA averaged at 58). The Quaternary provenance of the NW-SCS did not undergo significant changes, recording mixed sedimentation from the Red River, Hainan Island, and central Vietnamese sources. The felsic source rocks and negative Eu anomaly indicated the shelf area received sediments primarily from the Red River and Hainan Island. However, a positive Eu anomaly on the shelf margin suggests additional contributions from mafic rocks sourced from central Vietnam. During the MPT (1.3–1.4 to 0.8–0.9 Ma), the dominant periodicity of climate cycles changed from a 40 kyr obliquity cycle to a 100 kyr eccentricity cycle; the cooling climate led to a slight weaking in chemical weathering and a minor decrease in sediment supply from terrestrial sources. After the MPT, the mixed sourced sediments in the shelf and shelf margin areas of the NW-SCS likely suffered from multiple hydrodynamic forces under the influence of the Pleistocene high-frequency and high-amplitude sea level fluctuations. These climate induced changes led to significant fluctuations in element content that provide new insights into Quaternary sources and climatic events in the NW-SCS.

Spatial and temporal variability of meteorological droughts including atmospheric circulation in Central Europe

Drought is one of the natural phenomena influencing many aspects of human activities like water scarcity, food production, agriculture, industry and ecological conditions of the environment. For decades, drought has caused huge financial losses in Europe and around the world. In the area of the Polish Carpathians, there are periods with a deficit of rainwater and increasing frequency of dry months especially in the cold half-year. However, only a limited number of studies exist about the spatial and temporal variability of meteorological drought and the main mechanisms determining its performance in Central Europe. The aim of this work is to perform the spatial and temporal analysis of drought, expressed as SPI, in a heterogenous area of the Polish Carpathian and the highland region in the East-Central part of Europe based on long-term precipitation data. Moreover, for the first time in this work drought characteristics assessed by means of the SPI were discussed considering the atmospheric circulation calendar. In this work monthly precipitation from 55 rainfall stations were analysed from 1961 to 2022. The 3-, 6-, 9-, and 12-month Standardized Precipitation Index (SPI) was used as indicators of meteorological drought. For the 3-month SPI, the main climatic mechanisms determining extreme droughts were defined based on the calendar of synoptic circulations. The Mann-Kendall test was used to detect the trend of extreme droughts. Statistically significant trends of SPI were observed on 52.7% of all analyzed stations and, in most cases, a positive trend was observed, indicating an increase in water resources in the Upper Vistula Basin. Statistically significant trends were more frequently observed in stations located in the western part of the analyzed region. Long-term droughts, represented by the 12-month SPI, occurred in all stations but not in all years. Short-term droughts (3-month SPI) were most frequent in the winter season, 6- and 9-month SPI in winter and spring, and 12-month SPI in winter and autumn. The spatial distribution of droughts was highly diverse. The most intensive drought occurred in 1984, with the 6-month SPI covering 98% of the analyzed region, and the 9- and 12-month SPI covering 90% of the entire region. Droughts exhibit a seasonal pattern, with a dominant 10-year periodicity for all analyzed variants of SPI. Additionally, Fourier analysis revealed a 2-year periodicity for the 3-, 6-, and 9-month SPI and a 31-year periodicity for the 12-month SPI. The results provide insights into the typical climatic conditions in Poland, with strong seasonality in precipitation. The study highlighted that short-term extreme droughts, represented by the 3-month SPI, are often caused by anticyclonic situations with high-pressure wedges Ka and Wa, as observed in 52.3% of cases. These findings are crucial for understanding the spatial and temporal variability of short and long-term extreme droughts in Central Europe, particularly for the agriculture sector which is dominant in the northern part of the analyzed region, where drought frequency is highest.

Coccidioidomycosis seasonality in California: a longitudinal surveillance study of the climate determinants and spatiotemporal variability of seasonal dynamics, 2000–2021

Coccidioidomycosis, an emerging fungal disease in the western USA, exhibits seasonal patterns that are poorly understood, including periods of strong cyclicity, aseasonal intervals, and variation in seasonal timing that have been minimally characterized, and unexplained as to their causal factors. Coccidioidomycosis incidence has increased markedly in recent years, and our limited understanding of intra- and inter-annual seasonality has hindered the identification of important drivers of disease transmission, including climate conditions. In this study, we aim to characterize coccidioidomycosis seasonality in endemic regions of California and to estimate the relationship between drought conditions and coccidioidomycosis seasonal periodicity and timing. We analysed data on all reported incident cases of coccidioidomycosis in California from 2000 to 2021 to characterize seasonal patterns in incidence, and conducted wavelet analyses to assess the dominant periodicity, power, and timing of incidence for 17 counties with consistently high incidence rates. We assessed associations between seasonality parameters and measures of drought in California using a distributed lag nonlinear modelling framework. All counties exhibited annual cyclicity in incidence (i.e., a dominant wavelet periodicity of 12 months), but there was considerable heterogeneity in seasonal strength and timing across regions and years. On average, 12-month periodicity was most pronounced in the Southern San Joaquin Valley and Central Coast. Further, the annual seasonal cycles in the Southern San Joaquin Valley and the Southern Inland regions occurred earlier than those in coastal and northern counties, yet the timing of annual cycles became more aligned among counties by the end of the study period. Drought conditions were associated with a strong attenuation of the annual seasonal cycle, and seasonal peaks became more pronounced in the 1-2 years after a drought ended. We conclude that drought conditions do not increase the risk of coccidioidomycosis onset uniformly across the year, but instead promote increased risk concentrated within a specific calendar period (September to December). The findings have important implications for public health preparedness, and for how future shifts in seasonal climate patterns and extreme events may impact spatial and temporal coccidioidomycosis risk. National Institutes of Health.

Thermal structure variations and influence factors in a subtropical reservoir, China: explanations from multiple research methods

ABSTRACT Revealing the subtle variations in thermal structure in a reservoir is crucial for accurately understanding the interaction between water and the carbon cycle. This study provides a detailed description of the thermal structure of Dalongdong reservoir, a representative subtropical stratified reservoir in Guangxi, China. It unveils the three stable state changes in water – mixing, microstratification, and stratification – along with their influencing factors. The study emphasizes air temperature (AT) as the primary factor influencing water temperature (WT) stability, followed by water level. Cross-correlation analysis shows that adjacent WTs experience a prolonged response hysteresis during the stratification period, while the mixing period exhibits a shorter hysteresis. Wavelet analysis revealed that AT and surface-layer WT exhibited a dominant oscillation period of 16–32 h. The periodicity of other water layers is not obvious. This framework can help to enhance our understanding of material cycles and protection of the water environment.

COVID-19 Vaccine Effectiveness Studies against Symptomatic and Severe Outcomes during the Omicron Period in Four Countries in the Eastern Mediterranean Region.

Vaccine effectiveness (VE) studies provide real-world evidence to monitor vaccine performance and inform policy. The WHO Regional Office for the Eastern Mediterranean supported a regional study to assess the VE of COVID-19 vaccines against different clinical outcomes in four countries between June 2021 and August 2023. Health worker cohort studies were conducted in 2707 health workers in Egypt and Pakistan, of whom 171 experienced symptomatic laboratory-confirmed SARS-CoV-2 infection. Test-negative design case-control studies were conducted in Iran and Jordan in 4017 severe acute respiratory infection (SARI) patients (2347 controls and 1670 cases) during the Omicron variant dominant period. VE estimates were calculated for each study and pooled by study design for several vaccine types (BBIBP-CorV, AZD1222, BNT162b2, and mRNA-1273, among others). Among health workers, VE against symptomatic infection of a complete primary series could only be computed compared to partial vaccination, suggesting a benefit of providing an additional dose of mRNA vaccines (VE: 88.9%, 95%CI: 15.3-98.6%), while results were inconclusive for other vaccine products. Among SARI patients, VE against hospitalization of a complete primary series with any vaccine compared to non-vaccinated was 20.9% (95%CI: 4.5-34.5%). Effectiveness estimates for individual vaccines, booster doses, and secondary outcomes (intensive care unit admission and death) were inconclusive. Future VE studies will need to address challenges in both design and analysis when conducted late during a pandemic and will be able to utilize the strengthened capacities in countries.

Compounding impacts of the earthquake and submarine landslide on the Toyama Bay tsunami during the January 2024 Noto Peninsula event

The January 2024 Noto Peninsula earthquake (Mw 7.6) generated a destructive tsunami in the Sea of Japan region. Locally, inside Toyama Bay, the tsunami arrived at the Toyama wave and tide gauges within 2–3 min of the earthquake. Such an early tsunami arrival is inconsistent with the epicentral distance of ∼60 km. The travel time of the earthquake-induced tsunami is anticipated to be around 20 min, which is confirmed through tsunami simulations. Based on spectral and wavelet analyses of the Toyama tide and wave gauge records, we found 5 min, 14 min, and 32 min dominant wave periods. The shorter wave periods of 5 and 14 min are likely associated with a submarine landslide due to their early arrivals, as evidenced in our wavelet analysis. We then identified a potential submarine landslide location using the tsunami back-propagated travel time technique and visual inspection of the bathymetric profile. Conducting several simulations and comparing simulated and observed waveforms, we identified a seafloor landslide length of approximately 3000 m located ∼4 km offshore Toyama City. Our combined earthquake-landslide source model better reproduces the tsunami observations, indicating the contribution of the submarine landslide to the January 2024 Noto Peninsula tsunami.

Variability in COVID-19 symptom presentation during pregnancy and its impact on maternal and infant outcomes across the pandemic

BackgroundWith the dominance of different SARS-CoV-2 variants, the severity of COVID-19 has evolved. We aimed to investigate the difference in symptom prevalence and the association between symptoms and adverse pregnancy outcomes during the dominance of Wild-type/Alpha, Delta, and Omicron. MethodsCOVID-19 related symptom prevalence, maternal and specific neonatal outcomes of 5431 pregnant women registered in this prospective study were compared considering the dominant virus variant. Logistic regression models analyzed the association between specific symptoms and intensive care unit (ICU) admission or preterm birth. ResultsInfection with the Delta variant led to an increase in the symptom burden compared to the Wild-type/Alpha variant and the highest risk for respiratory tract symptoms, feeling of sickness, headache, and dizziness/drowsiness. An infection with the Omicron variant was associated with the lowest risk of dyspnea and changes in smell/taste but the highest risk for nasal obstruction, expectoration, headaches, myalgia, and fatigue compared to the Wild-type/Alpha and Delta variant dominant periods. With the progression of the Wild-type/Alpha to the Delta variant neonatal outcomes worsened. Dyspnea and fever were strong predictors for maternal ICU admission and preterm birth independent of vaccination status or trimester of infection onset. ConclusionThe symptom burden increased during the Delta period and was associated with worse pregnancy outcomes than in the Wild-type/Alpha area. During the Omicron dominance there still was a high prevalence of less severe symptoms. Dyspnea and fever can predict a severe maternal illness.

Diverse Orbital‐Scale Variations of Precipitation Oxygen Isotopes in the Northern Hemisphere Mid‐Latitudes: A Comparative Study Between East Asia and North America

AbstractThe oxygen isotope (δ18O) records of paleo‐precipitation contain abundant information on past climate changes. Nevertheless, at the orbital scale, our current understanding about the characteristics and mechanisms of precipitation oxygen isotope (δ18Op) variations in the Northern Hemisphere (NH) mid‐latitudes remains limited due to the lack of abundant long‐term geological records. In this study, based on a 300‐ka transient simulation involving stable isotope fractionation processes, we systematically analyzed the characteristics of the orbital‐scale δ18Op variations and their potential mechanisms, especially in two representative regions: mid‐latitude East Asia (MEA) and mid‐latitude North America (MNA) located in the Eastern and Western Hemispheres respectively. Our findings reveal that the MEA δ18Op is dominated by a 23‐ka cycle, ultimately driven by the precession‐induced insolation variation; while the MNA δ18Op primarily exhibits a 100‐ka glacial‐interglacial cycle and is eventually governed by the ice volume forcing. The δ18Op changes in these two regions not only present diverse dominant cycles and forcing factors, but also involve distinct physical processes. In MEA, water vapor transport by the westerly circulation during the rainy season (May–August) is the key process linking the April–July boreal insolation with the annual/rainy‐season δ18Op variations. In contrast, the annual δ18Op changes in MNA mainly depend on the water vapor transport processes triggered by the expansion and retreat of the North American ice sheet, albeit with certain influence of the temperature effect as well. These results suggest that the dominant periodicities and forcing mechanisms of the orbital‐scale δ18Op variations across the NH mid‐latitudes are complex and varied.

Wavelet-based analysis of hydro-climatic and vegetation dynamics in heterogeneous agro-climatic zones of East Africa

ABSTRACT Natural and human-induced factors profoundly affect agricultural crop production in East Africa, sparking ongoing debates about their relative significance. This study investigates the impact of localized hydro-climatic variables like precipitation, temperature, vapor pressure deficit, and water deficit on crop production. Additionally, it examines climate oscillations such as El Niño-Southern Oscillation (ENSO), Indian Ocean Dipole (IOD), North Atlantic Oscillation (NAO), and Pacific Decadal Oscillation (PDO). Employing the Normalized Difference Vegetation Index (NDVI) metric, analysis focuses on four climatic zones, ranging from arid to humid. Results suggest that the dominant periodicities for NDVI and hydro-climatic factors are annual (8-16 months) and intra-annual (4-8 months), while circulation indices exhibit inter-annual and inter-decadal periodicity. The study reveals that vegetation dynamics are more sensitive to annual and intra-annual fluctuations in hydro-climatic factors compared to inter-annual and inter-decadal oscillations in circulation indices. The bi-variate wavelet coherence (WTC) analysis reveals that precipitation and ENSO are the most significant factors explaining vegetation variability, while multiple wavelet coherence (MWC) analysis demonstrates that all variables contribute significantly to NDVI variability. This research underscores the importance of wavelet techniques in deciphering complex relationships between hydro-climatic factors and crop production, with implications for agricultural management and policy in East Africa.

Energy inputs imprint seasonality and fractal structure on river metabolic regimes

AbstractThe temporal structures of gross primary production (GPP) and ecosystem respiration (ER) vary across time scales in response to complex interactions among dynamic drivers (e.g., flow, light, temperature, organic matter supply). To explore emergent patterns of river metabolic variation, we applied frequency‐domain analysis to multiyear records of metabolism across 87 US rivers. We observed a dominant annual periodicity in metabolic variation and universal fractal scaling (i.e., power spectral density inversely correlated with frequency) at subannual frequencies, suggesting these are foundational temporal structures of river metabolic regimes. Frequency‐domain patterns of river metabolism aligned best with drivers related to energy inputs: benthic light for GPP and GPP for ER. Simple river metabolism models captured frequency‐domain patterns when parameterized with appropriate energy inputs but neglecting temperature controls. These results imply that temporal variation of energy supply imprints directly on metabolic signals and that frequency‐domain patterns provide benchmark properties to predict river metabolic regimes.

A comprehensive study of an oscillating eclipsing Algol: Y Camelopardalis

Abstract Y Camelopardalis (Y Cam) is classified as one of the oscillating eclipsing Algol (oEA) systems, which feature a $\delta$ Scuti-type pulsating component alongside mass transfer phenomena. oEA systems are invaluable for probing the evolutionary processes and internal structures of binary components, offering insights through their binary variations and oscillations. In this study, we conducted a comprehensive investigation of Y Cam utilizing high-quality photometric TESS data and high-resolution ELODIE spectra. Through our analysis, we examined the radial velocity variation, performed binary modeling, and calculated the effective temperature values of binary components. The fundamental stellar parameters, such as mass and radius, were determined with an accuracy of $\sim$2%–6%. Furthermore, we examined the orbital period variation to assess the amount of mass transfer using the available minima times of the system and three new minima times obtained from TESS light curves. Analyzing the pulsation structure of the system with the TESS data revealed the dominant pulsation period and amplitude of the pulsating component to be 0.066 d and 4.65 mmag, respectively. Notably, we observed frequency modulations with the orbital period’s frequency, along with variations in the amplitude of the highest amplitude frequency across different orbital phases. Remarkably, the amplitude reaches its peak at phases 0.5 and 1. These findings indicate a candidate for a tidally tilted pulsator. Consequently, we investigated the evolutionary status of the binary components using MESA binary evolution models, determining the age of the system to be 3.28 ± 0.09 Gyr.

COVID-19 infections in English schools and the households of students and staff 2020-21: a self-controlled case-series analysis.

The role of children and staff in SARS-CoV-2 transmission outside and within households is still not fully understood when large numbers are in regular, frequent contact in schools. We used the self-controlled case-series method during the alpha- and delta-dominant periods to explore the incidence of infection in periods around a household member infection, relative to periods without household infection, in a cohort of primary and secondary English schoolchildren and staff from November 2020 to July 2021. We found the relative incidence of infection in students and staff was highest in the 1-7 days following household infection, remaining high up to 14 days after, with risk also elevated in the 6--12 days before household infection. Younger students had a higher relative incidence following household infection, suggesting household transmission may play a more prominent role compared with older students. The relative incidence was also higher among students in the alpha variant dominant period. This analysis suggests SARS-CoV2 infection in children, young people and staff at English schools were more likely to be associated with within-household transmission than from outside the household, but that a small increased risk of seeding from outside is observed.

Vaccination status and disease severity of COVID-19 in different phases of the pandemic

ABSTRACT This study aimed to explore the clinical profile and the impact of vaccination status on various health outcomes among COVID-19 patients diagnosed in different phases of the pandemic, during which several variants of concern (VOCs) circulated in South Carolina (SC). The current study included 861,526 adult COVID-19 patients diagnosed between January 2021 and April 2022. We extracted their information about demographic characteristics, vaccination, and clinical outcomes from a statewide electronic health record database. Multiple logistic regression models were used to compare clinical outcomes by vaccination status in different pandemic phases, accounting for key covariates (e.g. historical comorbidities). A reduction in mortality was observed among COVID-19 patients during the whole study period, although there were fluctuations during the Delta and Omicron dominant periods. Compared to non-vaccinated patients, full-vaccinated COVID-19 patients had lower mortality in all dominant variants, including Pre-alpha (adjusted odds ratio [aOR]: 0.33; 95%CI: 0.15–0.72), Alpha (aOR: 0.58; 95%CI: 0.42–0.82), Delta (aOR: 0.28; 95%CI: 0.25–0.31), and Omicron (aOR: 0.29; 95%CI: 0.26–0.33) phases. Regarding hospitalization, full-vaccinated parties showed lower risk of hospitalization than non-vaccinated patients in Delta (aOR: 0.44; 95%CI: 0.41–0.47) and Omicron (aOR: 0.53; 95%CI: 0.50–0.57) dominant periods. The findings demonstrated the protection effect of the COVID-19 vaccines against all VOCs, although some of the full-vaccinated population still have symptoms to varying degrees from COVID-19 disease at different phases of the pandemic.