Synchronized movement between US lumber futures and southern pine sawtimber prices and COVID-19 impacts

We analyzed the synchronized movements of lumber futures and southern pine sawtimber stumpage prices in the United States since 2011 and their response to COVID-19 events using wavelet analysis and event study. We found that the sawtimber and lumber prices have followed complex comovement patterns in the time-frequency domain and both reacted to COVID-19 events with a higher response intensity of the lumber price. Although they reacted differently to the early COVID-19 episodes and vaccine news, the sawtimber and lumber prices responded similarly to the COVID-19 pandemic declarations by the World Health Organization and US president, the US Food and Drug Administration panel’s recommendation of the first COVID-19 vaccine, and economic stimulus legislation. The patterns of synchronized movements between the sawtimber and lumber prices varied with time and frequency, but their comovement at low frequencies (>64 weeks) has strengthened since 2014 and been led by the lumber futures price; COVID-19 episodes have not changed this trend. The different magnitude of response of the two prices to the COVID-19 related events, as well as the long-term dominance of the lumber price in the comovement, reveals asymmetric price negotiation power and benefit distributions among the agents of the lumber value chain.

Prehospital Period in Patients with COVID-19: Cardiovascular Comorbidity and Pharmacotherapy During the First Epidemic Wave (Hospital Registry Data)

Aim. Based on the data from the register of patients with COVID-19 and community-acquired pneumonia (CAP), analyze the duration of the prehospital period, cardiovascular comorbidity and the quality of prehospital pharmacotherapy of concomitant cardiovascular diseases (CVD).Material and methods. Patients were included to the study which admitted to the FSBI "NMHC named after N.I. Pirogov" of the Ministry of Health of the Russian Federation with a suspected or confirmed diagnosis of COVID-19 and/or CAP. The data for prehospital therapy, information from medical histories and a patients’survey in the hospital or by telephone contact 1-2 weeks after discharge were study. The duration of the prehospital stage was determined from the date of the appearance of clinical symptoms of coronavirus infection to the date of hospitalization.Results. The average age of the patients (n=1130; 579 [51.2%] men and 551 [48.8%] women) was 57.5±12.8 years. The prehospital stage was 7 (5,0; 10,0) days and did not differ significantly in patients with the presence and absence of CVD, but was significantly less in the deceased than in the surviving patients, as well as in those who required artificial lung ventilation (ALV). 583 (51.6%) patients had at least one CVD. Cardiovascular comorbidity was registered in 222 (42.7%) patients with hypertension, 210 (95.5%) patients with coronary heart disease (CHD), 104 (91.2%) patients with atrial fibrillation (AF). The inclusion of non-cardiac chronic diseases in the analysis led to an increase in the total proportion of patients with concomitant diseases to 65.8%. Approximately a quarter of hypertensive patients did not receive antihypertensive therapy, a low proportion of patients receiving antiplatelet agents and statins for CHD was revealed – 53% and 31.8%, respectively, anticoagulants for AF – 50.9%.Conclusion. The period from the onset of symptoms to hospitalization was significantly shorter in the deceased than in the surviving patients, as well as in those who required ALV. The proportion of people with a history of at least one CVD was about half of the entire cohort of patients. In patients with CVD before COVID-19 disease, a low frequencies of prescribing antihypertensive drugs, statins, antiplatelet agents and anticoagulants (in patients with AF) were recorded at the prehospital stage.

SARS-CoV-2 variants with reduced infectivity and varied sensitivity to the BNT162b2 vaccine are developed during the course of infection

In-depth analysis of SARS-CoV-2 quasispecies is pivotal for a thorough understating of its evolution during infection. The recent deployment of COVID-19 vaccines, which elicit protective anti-spike neutralizing antibodies, has stressed the importance of uncovering and characterizing SARS-CoV-2 variants with mutated spike proteins. Sequencing databases have allowed to follow the spread of SARS-CoV-2 variants that are circulating in the human population, and several experimental platforms were developed to study these variants. However, less is known about the SARS-CoV-2 variants that are developed in the respiratory system of the infected individual. To gain further insight on SARS-CoV-2 mutagenesis during natural infection, we preformed single-genome sequencing of SARS-CoV-2 isolated from nose-throat swabs of infected individuals. Interestingly, intra-host SARS-CoV-2 variants with mutated S genes or N genes were detected in all individuals who were analyzed. These intra-host variants were present in low frequencies in the swab samples and were rarely documented in current sequencing databases. Further examination of representative spike variants identified by our analysis showed that these variants have impaired infectivity capacity and that the mutated variants showed varied sensitivity to neutralization by convalescent plasma and to plasma from vaccinated individuals. Notably, analysis of the plasma neutralization activity against these variants showed that the L1197I mutation at the S2 subunit of the spike can affect the plasma neutralization activity. Together, these results suggest that SARS-CoV-2 intra-host variants should be further analyzed for a more thorough characterization of potential circulating variants.

Increase the Efficiency of an Induction Motor Feed from Inverter for Low Frequencies by Combining Design and Control Improvements

Speed-controlled induction motors have the most significant potential for energy savings. The greatest problems with obtaining high efficiency occur in motors with a wide range of rotational speed regulation, as in the motors for driving industrial washing machines under consideration. While for the highest speeds, the dominant phenomenon is at field weakening. The problem is obtaining the optimal size of the magnetic flux for low rotation speed to prevent excessive saturation increasing current, and reduction of efficiency. This problem is usually solved by selecting the appropriate control for an already built machine. The authors propose a combination of activities when designing the motor structure with the selection of proper control, which allows for high efficiency. Since the drive does not require precise speed control or obtaining the required dynamics, it was possible to use an inexpensive control in an open loop, avoiding the cost of transmitters. Furthermore, the number of design parameters that are subject to change is significantly limited by technological factors and the available space in the washing machine. Proper parameter selection was made using a peripheral method assisted by field-circuit simulations. The proposed approach can be used in designing structures and selecting motors controls for other applications.

Local interactions between steady-state visually evoked potentials at nearby flickering frequencies

Steady-state visually evoked potentials (SSVEP) are widely used to index top-down cognitive processing in human electroencephalogram (EEG) studies. Typically, two stimuli flickering at different temporal frequencies (TFs) are presented, each producing a distinct response in the EEG at its flicker frequency. However, how SSVEP responses in EEG are modulated in the presence of a competing flickering stimulus just due to sensory interactions is not well understood. We have previously shown in local field potentials (LFP) recorded from awake monkeys that when two overlapping full screen gratings are counter-phased at different TFs, there is an asymmetric SSVEP response suppression, with greater suppression from lower TFs, which further depends on the relative orientations of the gratings (stronger suppression and asymmetry for parallel compared to orthogonal gratings). Here, we first confirmed these effects in both male and female human EEG recordings. Then, we mapped the response suppression of one stimulus (target) by a competing stimulus (mask) over a much wider range than the previous study. Surprisingly, we found that the suppression was not stronger at low frequencies in general, but systematically varied depending on the target TF, indicating local interactions between the two competing stimuli. These results were confirmed in both human EEG and monkey LFP and electrocorticogram (ECoG) data. Our results show that sensory interactions between multiple SSVEPs are more complex than shown previously and are influenced by both local and global factors, underscoring the need to cautiously interpret the results of studies involving SSVEP paradigms.

Galvanic Corrosion Study between Tensile-Stressed and Non-Stressed Carbon Steels in Simulated Concrete Pore Solution

The present study investigated the galvanic effect between tensile-stressed and non-stressed carbon steels, in addition to the influence of the tensile stress on the passivation and corrosion behavior of steel in a simulated concrete pore solution. Three different levels of tensile stress, ranging from elastic to plastic stress on the surface, were applied by adjusting the displacement of C-shape carbon steel rings. Different electrochemical measurements including the open circuit potential (OCP), the electrochemical impedance spectroscopy (EIS), the zero-resistance ammetry (ZRA), and the cyclic polarization were performed. Based on the results of EIS, the tensile stress degraded the resistance of the oxide film in moderate frequencies while enhancing the charge transfer resistance in low frequencies during passivation. As corrosion propagated, the stressed steel yielded a similar charge transfer resistance to or an even lower charge transfer resistance than the non-stressed steel, especially in the case of plastic tensile stress. The galvanic effect between the tensile-stressed and non-stressed steels increased the chloride threshold value of the tensile-stressed steel, although the susceptibility to pitting corrosion was exhibited after being corroded.

Theta- and gamma-band oscillatory uncoupling in the macaque hippocampus

Nested hippocampal oscillations in the rodent gives rise to temporal coding that may underlie learning, memory, and decision making. Theta/gamma coupling in rodent CA1 occurs during exploration and sharp-wave ripples during quiescence. Whether these oscillatory regimes extend to primates is less clear. We therefore sought to identify correspondences in frequency bands, nesting, and behavioral coupling taken from macaque hippocampus. We found that, in contrast to the rodent, theta and gamma frequency bands in macaque CA1 were segregated by behavioral states. Beta/gamma (15-70Hz) had greater power during visual search while theta (7-10 Hz) dominated during quiescence. Moreover, delta/theta (3-8 Hz) amplitude was strongest when beta2/slow gamma (20-35 Hz) amplitude was weakest, though the low frequencies coupled with higher, ripple frequencies (60-150 Hz). The distribution of spike-field coherence revealed three peaks matching the 3-10 Hz, 20-30 Hz and 60-150 Hz bands; however, the low frequency effects were primarily due to sharp-wave ripples. Accordingly, no intrinsic theta spiking rhythmicity was apparent. These results support a role for beta2/slow gamma modulation in CA1 during active exploration in the primate that is decoupled from theta oscillations. These findings diverge from the rodent oscillatory canon and call for a shift in focus and frequency when considering the primate hippocampus.

Introduction to this special section: Seismic acquisition

In the life cycle of a seismic product, the lion's share of the budget and personnel hours is spent on acquisition. In most modern seismic surveys, acquisition involves hundreds of specialized personnel working for months or years. Seismic acquisition also must overcome potential liabilities and health, safety, and environmental concerns that rival facility, pipeline, construction, and other operational risks. As only properly acquired data can contribute effectively to processing and interpretation strategies, a great deal of importance is placed on acquisition quality. Arguably, many of the advances the seismic industry has experienced find their origin arising from advances in acquisition techniques. Full-waveform inversion (FWI), for example, can reach its full potential only when seismic acquisition has provided both low frequencies and long offsets.

Discovering formation of ice 0 by low-frequency measurement data

In this work, low-frequency characteristics of wetted nanoporous silicate materials were measured, as well as the specimen’s own low-frequency electric fluctuations at the frequencies of 1…100 Hz. The measurements at low frequencies were conducted at different voltages of the probing signal. A capacity cell was used in making the measurements. In the experiments, at the temperatures below –25…–30 °C, non-linearity of the medium was discovered. The experiments on the study of the specimen’s own electric fluctuations at these temperatures revealed their essential increase. These temperatures are below the point of phase transition of supercooled water to recently discovered ferroelectric ice 0. Based on the measurements made, a conclusion was made regarding formation of this modification of ice in the nanosize pores of the wetted materials under study. Ice 0 is a ferroelectric; therefore, its formation from deeply supercooled water may have a significant impact on the electric parameters of wetted bodies at the temperatures below –23 °C. At the interface of such ice with another dielectric, a thin layer with practically metallic conductivity emerges. Such a layer influences not only the non-linear dependence of dielectric permittivity on the electric field but also increases attenuation of electromagnetic radiation in a medium.