The difficulties of diagnosis of neurosyphilis at the modern stage

На современном этапе в России наблюдается тенденция к увеличению регистрации случаев нейросифилиса на фоне снижения заболеваемости сифилитической инфекцией в целом. Рост заболеваемости нейросифилисом отражает ситуацию с повышением частоты первичных форм сифилиса в конце 90-х – начале 2000-х годов, когда в нашей стране разразилась эпидемия этого заболевания. По мнению большинства специалистов, бледная трепонема всегда попадает в нервную систему, причем в одних случаях ее присутствие является транзиторным, а в других наблюдается асимптомное персистирование, в третьих манифестирует нейросифилис. В настоящее время лечение сифилиса проводится чаще всего амбулаторно дюрантными формами (бензатинбензилпенициллины), которые создают длительную (в течение нескольких суток и вплоть до 18‑21 дня после однократного введения), но низкую концентрацию пенициллина в организме. Препараты плохо преодолевают гематоэнцефалический барьер, следовательно, при недиагностированном скрытом сифилитическом менингите не достигается санация ликвора и сохраняется возможность развития поздних манифестных форм нейросифилиса. Авторы описывают трудности диагностики нейросифилиса и приводят клинический случай ишемического инсульта у молодого больного с нейросифилисом. Лабораторные данные подтвердили наличие сифилиса, а ликворологическое обследование и клинические данные позволили установить диагноз менинговаскулярного сифилиса. Авторы отмечают, что особого внимания требует соблюдение алгоритма клинико-лабораторного обследования пациентов при наличии у них нарушений функции центральной и периферической нервной системы, органов зрения и слуха независимо от давности предполагаемого заражения и предполагаемой серорезистентности. Поскольку нейросифилис является междисциплинарной проблемой, необходимо комплексное клинико-лабораторное и клинико-инструментальное обследование пациентов с участием врачей разного профиля. At the modern stage in Russia, we can observe the tendency of increase in recording cases of neurosyphilis against the background of reduction of morbidity rate of syphilitic infection in general. Increase of neurosyphilis morbidity reflects the situation of frequency increase of primary forms of syphilis in the end of the 90s – beginning of the 2000s, when our country faced with epidemic of this disease. Most experts assume that treponema pallidum always penetrates in the nervous system, in some cases its presence being transitory, in other cases, we observe asymptomatic persistence, and in some, neurosyphilis manifests. Currently, most often syphilis therapy takes place on outpatient basis with repository forms ((Benzathine benzylpenicillins) which create long (during several days and up to 18-21 days after one-time administration), but low concentration of penicillin in the body. These drugs badly overcome blood-brain barrier, consequently, if syphilitic meningitis is latent and not diagnosed, liquor sanation is not achieved, and potential development of neurosyphilis manifest forms is retained. The authors describe the difficulties of diagnosis of neurosyphilis and a clinical case of ischemic stroke in a young patient with neurosyphilis. Diagnosis of syphilis was confirmed by laboratory studies; liquor tests and clinical data allowed to diagnose meningovascular syphilis. The authors highlight that special attention should be paid to observance of algorithm of clinical-laboratory examination of patients if they have disorders in functions of central and peripheral nervous systems, organs of vision and hearing, regardless of remoteness of supposed infection and supposed seroresistance. As neurosyphilis is interdisciplinary problem, complex clinical-laboratory and clinical-instrumental examination of patients is required, involving medical specialists of different profiles.

Spread of Endemic SARS-CoV-2 Lineages in Russia Before April 2021

In 2021, the COVID-19 pandemic is characterized by global spread of several lineages with evidence for increased transmissibility. Russia is among the countries with the highest number of confirmed COVID-19 cases, making it a potential hotspot for emergence of novel variants. Here, we show that among the globally significant variants of concern, alpha (B.1.1.7), beta (B.1.351) or gamma (P.1), none have been sampled in Russia before January 2021. Instead, between summer 2020 and spring 2021, the epidemic in Russia has been characterized by the spread of two lineages that are rare elsewhere: B.1.1.317 and a sublineage of B.1.1 including B.1.1.397 (hereafter, B.1.1.397+). Their frequency has increased in different parts of Russia. Mutational composition and frequency dynamics suggest that B.1.1.317 and B.1.1.397+ may be more transmissible than the previously predominant B.1.1. On top of these lineages, in January 2021, B.1.1.7 emerged in Russia, reaching the frequency of 17.4% (95% C.I.: 12.0%-24.4%) in March 2021. Additionally, we identify three novel distinct lineages, AT.1, B.1.1.524 and B.1.1.525, that have started to spread, together reaching the frequency of 11.8% (95% C.I.: 7.5%-18.1%) in March 2021. These lineages carry combinations of several notable mutations, including the S:E484K mutation of concern, deletions at a recurrent deletion region of the spike glycoprotein (S:Δ140-142, S:Δ144 or S:Δ136-144), and nsp6:Δ106-108 (also known as ORF1a:Δ3675-3677). Community-based PCR testing indicates that these variants have continued to spread in April 2021, with the frequency of B.1.1.7 reaching 21.7% (95% C.I.: 12.3%-35.6%), and the joint frequency of B.1.1.524 and B.1.1.525, 15.2% (95% C.I.: 7.6%-28.2%). Although these variants have been displaced by the onset of delta variant in May-June 2021, the frequency increase of lineages B.1.1.317, B.1.1.397+, AT.1, B.1.1.524 and B.1.1.525 suggest that the combinations of mutations observed in them could have increased the rate of their spread.

The stability of dendritic growth in a binary alloy melt with buoyancy effect

On the basis of Xu’s interfacial wave theory, the stability of dendritic growth in a convective binary alloy melt with buoyancy effect is studied using the asymptotic method. The resulting asymptotic solution of equations reveals that the stability mechanism of dendritic growth in the binary alloy melt with buoyancy-driven convection is similar to that in a pure melt. Dendritic growth is stable above and unstable below a critical stability number [Formula: see text], which is determined by the quantization condition. In particular, there is a critical morphological number in the binary alloy melt. When the morphological number is less than the critical morphological number, the tip growth velocity increases, the tip curvature radius and oscillation frequency decrease, and the interface becomes thinner and smooth. When the morphological number is larger than the critical morphological number, the tip growth velocity decreases, the tip curvature radius and oscillation frequency increase, and the interface becomes fatter and rough. The result demonstrates that in a microgravity environment, there is a critical initial concentration such that below it thermal diffusion dominates, the tip growth velocity increases, the tip curvature radius and oscillation frequency decrease, and the interface becomes thinner and smooth; above it, solute diffusion dominates, the tip growth velocity decreases, the tip curvature radius and oscillation frequency increase, and the interface becomes fatter and rough.

Incomplete recovery to enhance economic growth losses from US hurricanes under global warming

Ongoing global warming is likely to increase the return frequency of very intense hurricanes in the North Atlantic. Here, we analyse how this frequency increase may impact on economic growth. To this end, we introduce an event-based macroeconomic growth model that allows us to assess how growth depends on the heterogeneity of hurricane impacts, by temporally resolving the economic response dynamics to individual hurricanes making landfall. We calibrate the model to hurricane impacts in the United States and find that economic growth losses scale super-linearly with the heterogeneity of hurricane impacts. We explain this by a disproportional increase of indirect losses with event severity which can lead to an incomplete recovery of the economy between consecutive intense landfall events. Based on two different methods to estimate the frequency increase of intense hurricanes, we estimate annual growth losses to increase by moderate 7% up to 146% in a 2°C world compared to the period 1980-2014. Our modelling suggests that higher insurance coverage may be a viable means to mitigate this climate change-induced increase in growth losses.

Flash Flood Events along the West Mediterranean Coasts: Inundations of Urbanized Areas Conditioned by Anthropic Impacts

Flash floods represent one of the natural hazards that causes the greatest number of victims in the Mediterranean area. These processes occur by short and intense rainfall affecting limited areas of a few square kilometers, with rapid hydrological responses. Among the causes of the flood frequency increase in the last decades are the effects of the urban expansion in areas of fluvial pertinence and climatic change, namely the interaction between anthropogenic landforms and hydro-geomorphological dynamics. In this paper the authors show a comparison between flood events with very similar weather-hydrological characteristics and the ground effects occurred in coastal areas of three regions located at the top of a triangle in the Ligurian Sea, namely Liguria, Tuscany and Sardinia. With respect to the meteorological-hydrological hazard, it should be noted that the events analyzed occurred during autumn, in the conditions of a storm system triggered by cyclogenesis on the Genoa Gulf or by the extra-tropical cyclone Cleopatra. The “flash floods” damage recorded in the inhabited areas is due to the vulnerability of the elements at risk in the fluvio-coastal plains examined. There are numerous anthropogenic forcings that have influenced the hydro-geomorphological dynamics and that have led to an increase in risk conditions.

Spread of endemic SARS-CoV-2 lineages in Russia

In 2021, the COVID-19 pandemic is characterized by global spread of several lineages with evidence for increased transmissibility. Russia is among the countries with the highest number of confirmed COVID-19 cases, making it a potential hotspot for emergence of novel variants. Here, we show that among the globally significant variants of concern, B.1.1.7 (501Y.V1), B.1.351 (501Y.V2) or P.1 (501Y.V3), none have been sampled in Russia before January 2021. Instead, since summer 2020, the epidemic in Russia has been characterized by the spread of two lineages that are rare elsewhere: B.1.1.317 and a sublineage of B.1.1 including B.1.1.397 (hereafter, B.1.1.397+). In February-March 2021, these lineages reached frequencies of 26.9% (95% C.I.: 23.1%-31.1%) and 32.8% (95% C.I.28.6%-37.2%) respectively in Russia. Their frequency has increased in different parts of Russia. Together with the fact that these lineages carry several spike mutations of interest, this suggests that B.1.1.317 and B.1.1.397+ may be more transmissible than the previously predominant B.1.1, although there is no direct data on change in transmissibility. Comparison of frequency dynamics of lineages carrying subsets of characteristic mutations of B.1.1.317 and B.1.1.397+ suggests that, if indeed some of these mutations affect transmissibility, the transmission advantage of B.1.1.317 may be conferred by the (S:D138Y+S:S477N+S:A845S) combination; while the advantage of B.1.1.397+ may be conferred by the S:M153T change. On top of these lineages, in January 2021, B.1.1.7 emerged in Russia, reaching the frequency of 17.4% (95% C.I.: 12.0%-24.4%) in March 2021. Additionally, we identify three novel distinct lineages, AT.1, and two lineages prospectively named B.1.1.v1 and B.1.1.v2, that have started to spread, together reaching the frequency of 11.8% (95% C.I.: 7.5%-18.1%) in March 2021. These lineages carry combinations of several notable mutations, including the S:E484K mutation of concern, deletions at a recurrent deletion region of the spike glycoprotein (S:Δ140-142, S:Δ144 or S:Δ136-144), and nsp6:Δ106-108 (also known as ORF1a:Δ3675-3677). Community-based PCR testing indicates that these variants have continued to spread in April 2021, with the frequency of B.1.1.7 reaching 21.7% (95% C.I.: 12.3%-35.6%), and the joint frequency of B.1.1.v1 and B.1.1.v2, 15.2% (95% C.I.: 7.6%-28.2%). The combinations of mutations observed in B.1.1.317, B.1.1.397+, AT.1, B.1.1.v1 and B.1.1.v2 together with frequency increase of these lineages make them candidate variants of interest.

Influence of Coflow On Buoyant Plume Puffing

The present study investigates the influence of an annular coflowing air stream on the puffing behaviour of a buoyant plume by employing the BiGlobal Linear Stability Analysis. An increase in the coflow is found to mitigate the puffing intensity and eventually stabilize the plumes. From the stability analysis, the critical coflow ratios, which represent the amount of coflow required to completely suppress the puffing, have been estimated for plumes spanning a wide range of non-dimensional parameters. The analysis shows that the critical coflow ratio largely depends on the two buoyancy parameters, the Froude number, and the density ratio whereas it remains marginally affected by the plume Reynolds number. Plumes with higher buoyancy require larger coflow for suppressing puffing. From the instability analysis, we have obtained a correlation law for critical coflow ratios in buoyant plumes. Also, it is found that the plume puffing frequency increases with an increase in the coflow. We attempt to ascertain the reasons for instability mitigation and frequency increase in the puffing plumes because of coflow.

A 4,000 year debris-flow record based on amphibious investigations of fan delta activity in Plansee (Austria, Eastern Alps)

The frequency of debris flows is hypothesized to increase in recent decades with enhanced rainstorm activity. Geological evidence to test this tendency for prehistoric times is scarce due to incomplete sediment records, complex stratigraphy, and insufficient age control especially in Alpine environments. In lacustrine archives, the link between onshore debris-flow processes and the depositional record in lake depocentres is poorly investigated. We present an amphibious characterization of alluvial fan deltas and a continuous 4,000 year debris-flow record from Plansee (Tyrol, Austria) combining Light detection and ranging (LiDAR) data, swath bathymetry, and sediment core analyses. The geomorphic investigation of two fan deltas in different developmental stages revealed a sediment delivery ratio of 7.9 % for the juvenile fan and no sediment transport into the lake on the mature fan within a 3-month summer period (May 2019–August 2019). Event deposits were dated and categorized according to their causal mechanism in a transect of four sediment cores. Debris flow-induced turbidites feature a more gradual fining-upward grain-size trend and higher TOC and δ13C values compared to earthquake-induced turbidites. Over the last 4,000 years, the record containing 138 debris flow-induced turbidites reveals four different debris-flow activity phases. Phase 1 (2050–1960 before the common era; BCE) depicts the second highest observed event frequencies. Phase 2 (1960 BCE–1550 common era; CE) shows large recurrence intervals. Phase 3 (1550–1905 CE) displays a gradual increase of event frequency. Phase 4 (1905–2018 CE) exhibits a debris-flow frequency increase between 1908 and 1928 CE, followed by the overall highest debris-flow frequency between 1928 and 1978 CE, and lower debris-flow frequencies since 1978 CE, which still exceed those of phase 1 to 3. Most remarkably, we find a ~7-fold increase of debris-flow frequency compared to the reference period 1700–1900 CE. The triggering of debris flows is more controlled by short intense rainstorms than for any other mass movement process and we demonstrate that lacustrine debris-flow records provide a unique inventory of hazard-relevant rainstorm frequencies over decades, centuries, and millennia. In a calibration period of 7 decades, we can show that the debris flow-induced turbidite record matches with the previously published debris-flow volume increase derived from aerial photography coincident to a pronounced rainstorm frequency increase. Here we show a millennium-scale debris-flow record that documents a ~7-fold increase in debris-flow frequencies in the 20th and 21st century coincident to 2-fold enhanced rainstorm activity in the Northern European Alps and provide a novel basis for systematic non-stationary estimation of future debris-flow frequencies in a changing climate.