Recurrent Phenomenon Research Articles

Significance of in-vivo biofilm in non-tuberculous mycobacterial diseases

There’s been a rise of pulmonary non-tuberculous mycobacterial (NTM) disease in developed countries. Treatment for this is limited and existing treatments have an extensive duration. The disease has a long latent period and often experiences recurrence after treatment. In their work, Senior Research Scientist Dr Kentaro Yamamoto and his team based at the Leprosy Research Centre within the Department of Mycobacteriology, National Institute of Infectious Diseases (NIID) are building on the recent discovery that NTMs form biofilms in infected tissues. There is potential that biofilms formed in infected tissues could shield the bacilli from drug exposure, protect them against the host’s immune system attacks, or offer a refuge for the bacilli within the human body. Therefore the researchers believe that the removal of biofilms formed by NTMs or M. tuberculosis in the body could represent a novel treatment approach. By developing a device that can easily detect mycobacterial biofilms within the body, it would be possible to non-invasively assess a patient’s condition, including the stage of infection. Much remains to be discovered about the structure and function of mycobacterial biofilms in vivo and so the researchers want to clarify the relationship between biofilm formation in the lungs and key factors such as pathogenicity, bacterial growth, drug resistance, host immune response and the phenomena of latency and recurrence. If the team can make these clarifications, the research will benefit patients who are allergic to antimicrobials and those whose quality of life is reduced by the long-term treatment of NTM disease.

Multi-temporal drought rarity curves—A yearly classification of meteorological drought severity in France

Droughts are recurrent phenomena that present a large variety of space and time patterns making rather difficult the assessment of their rarity and the comparison between events.Our study focuses on the “memory effect” of meteorological drought over France using the daily raingauge network maintained by Météo-France over 1950–2022. The proposed easy tool of rarity curves analyzes how drought events build and persist across time. The approach is purely statistic, assuming that drought consequences depend on the probability of non exceedance (“rarity”) of antecedent rainfall accumulations. In order to cover a large spectrum of “memory effects”, we consider a continuum of accumulation periods ranging from a few weeks to several years. The rarity curve of a given year displays the most severe rarity values encountered during the year as a function of the various accumulation periods (256 values ranging from 4 to 260 weeks in our case).Over the study period of 1950–2022 we show how the shape of rarity curves discriminate short- and long-term historical droughts. A k-means algorithm proves to be useful to classify the different years into typical drought situations from continuous drying to continuous wetting over the antecedent five years. Looking at the chronology of the found clusters also allows studying how droughts build and persist across time.

Gain-controlled taming of recurrent modulation instability

We show how the recurrence phenomenon characteristic of the nonlinear stage of induced modulational instability in a passive fiber is affected by forcing. An additional linear amplification, even if extremely weak, induces separatrix crossing corresponding to critical values of the gain around which the recurrence process considerably slows down, switching between dynamical orbits of different kind. We present evidence for such phenomenon in a fiber optics experiment where the gain is finely tuned by means of Raman amplification. A theoretical explanation is also provided that matches almost perfectly with our experimental results. Published by the American Physical Society 2024

Modeling environmental-born melioidosis dynamics with recurrence: An application of optimal control

Melioidosis is a significant health problem in tropical and subtropical regions, especially in Southeast Asia and Northern Australia. Recurrent melioidosis is a major obstacle to eliminating the disease from the community in these nations. This work aims to propose and analyze a human melioidosis model with recurrent phenomena and an optimal control model by incorporating time-dependent control functions. The basic reproduction number (R0) of the uncontrolled model is derived using the method of the next-generation matrix. Using the construction of a Lyapunov functional, we present the global asymptotic dynamics of the autonomous model in the presence of recurrent for both disease-free and endemic equilibria. The global asymptotic stability of the model’s equilibria shows the absence of a backward bifurcation for the model in both cases, whether in the absence or presence of relapse. The sensitivity analysis aims to identify the parameters that have the most significant impact on the model’s dynamics. Furthermore, qualitative analysis of the model’s global dynamics and the changing effect of the most influential parameters on R0 are supported by numerical experiments, with the results being illustrated graphically. The model with time-dependent controls is analyzed using optimal control theory to assess the impact of various intervention strategies on the spread of the epidemic. The numerical results of the optimality system are carried out using the Forward–Backward Sweep method in Matlab. We also conducted a cost-effectiveness analysis using two approaches: the average cost-effectiveness ratio and the incremental cost-effectiveness ratio.

Identification of KIFC1 as a putative vulnerability in lung cancers with centrosome amplification

Centrosome amplification (CA), an abnormal increase in the number of centrosomes in the cell, is a recurrent phenomenon in lung and other malignancies. Although CA promotes tumor development and progression by inducing genomic instability (GIN), it also induces mitotic stress that jeopardizes cellular integrity. CA leads to the formation of multipolar mitotic spindles that can cause lethal chromosome segregation errors. To sustain the benefits of CA by mitigating its consequences, malignant cells are dependent on adaptive mechanisms that represent therapeutic vulnerabilities. We aimed to discover genetic dependencies associated with CA in lung cancer. Combining a CRISPR/Cas9 functional genomics screen with tumor genomic analyses, we identified the motor protein KIFC1, also known as HSET, as a putative vulnerability specifically in lung adenocarcinoma (LUAD) with CA. KIFC1 expression was positively correlated with CA in LUAD and associated with worse patient outcomes, smoking history, and indicators of GIN. KIFC1 loss-of-function sensitized LUAD cells with high basal KIFC1 expression to potentiation of CA, which was associated with a diminished ability to cluster extra centrosomes into pseudo-bipolar mitotic spindles. Our work suggests that KIFC1 inhibition represents a novel approach for potentiating GIN to lethal levels in LUAD with CA by forcing cells to divide with multipolar spindles, rationalizing further studies to investigate its therapeutic potential.

From resonance to chaos by modulating spatiotemporal patterns through a synthetic optogenetic oscillator

Oscillations are a recurrent phenomenon in biological systems across scales, but deciphering their fundamental principles is very challenging. Here, we tackle this challenge by redesigning the wellcharacterised synthetic oscillator known as “repressilator” in Escherichia coli and controlling it using optogenetics, creating the “optoscillator”. Bacterial colonies manifest oscillations as spatial ring patterns. When we apply periodic light pulses, the optoscillator behaves as a forced oscillator and we systematically investigate the properties of the rings under various light conditions. Combining experiments with mathematical modeling, we demonstrate that this simple oscillatory circuit can generate complex dynamics that are transformed into distinct spatial patterns. We report the observation of synchronisation, resonance, subharmonic resonance and period doubling. Furthermore, we present evidence of a chaotic regime. This work highlights the intricate spatiotemporal patterns accessible by synthetic oscillators and underscores the potential of our approach in revealing fundamental principles of biological oscillations.

Genomics and proteomics to determine novel molecular subtypes and predict the response to immunotherapy and the effect of bevacizumab in glioblastoma

Glioblastoma (GBM) is a highly aggressive, infiltrative malignancy that cannot be completely cured by current treatment modalities, and therefore requires more precise molecular subtype signatures to predict treatment response for personalized precision therapy. Expression subtypes of GBM samples from the Cancer Genome Atlas (TCGA) were identified using BayesNM and compared with existing molecular subtypes of GBM. Biological features of the subtypes were determined by single-sample gene set enrichment analysis. Genomic and proteomic data from GBM samples were combined and Genomic Identification of Significant Targets in Cancer analysis was used to screen genes with recurrent somatic copy-number alterations phenomenon. The immune environment among subtypes was compared by assessing the expression of immune molecules and the infiltration of immune cells. Molecular subtypes adapted to immunotherapy were identified based on Tumor Immune Dysfunction and Exclusion (TIDE) score. Finally, least absolute shrinkage and selection operator (LASSO) logistic regression was performed on the expression profiles of S2, S3 and S4 in TCGA-GBM and RPPA to determine the respective corresponding best predictive model. Four novel molecular subtypes were classified. Specifically, S1 exhibited a low proliferative profile; S2 exhibited the profile of high proliferation, IDH1 mutation, TP53 mutation and deletion; S3 was characterized by high immune scores, innate immunity and adaptive immune infiltration scores, with the lowest TIDE score and was most likely to benefit from immunotherapy; S4 was characterized by high proliferation, EGFR amplification, and high protein abundance, and was the most suitable subtype for bevacizumab. LASSO analysis constructed the best prediction model composed of 13 genes in S2 with an accuracy of 96.7%, and the prediction model consisting of 17 genes in S3 with an accuracy of 86.7%, and screened 14 genes as components of the best prediction model in S4 with an accuracy of 93%. To conclude, our study classified reproducible and robust molecular subtypes of GBM, and these findings might contribute to the identification of patients responding to immunotherapy, thereby improving GBM prognosis.

Proteomic analysis of unicellular cyanobacterium Crocosphaera subtropica ATCC 51142 under extended light or dark growth.

The daily light-dark cycle is a recurrent and predictable environmental phenomenon to which many organisms, including cyanobacteria, have evolved to adapt. Understanding how cyanobacteria alter their metabolic attributes in response to subjective light or dark growth may provide key features for developing strains with improved photosynthetic efficiency and applications in enhanced carbon sequestration and renewable energy. Here, we undertook a label-free proteomic approach to investigate the effect of extended light (LL) or extended dark (DD) conditions on the unicellular cyanobacterium Crocosphaera subtropica ATCC 51142. We quantified 2287 proteins, of which 603 proteins were significantly different between the two growth conditions. These proteins represent several biological processes, including photosynthetic electron transport, carbon fixation, stress responses, translation, and protein degradation. One significant observation is the regulation of over two dozen proteases, including ATP dependent Clp-proteases (endopeptidases) and metalloproteases, the majority of which were upregulated in LL compared to DD. This suggests that proteases play a crucial role in the regulation and maintenance of photosynthesis, especially the PSI and PSII components. The higher protease activity in LL indicates a need for more frequent degradation and repair of certain photosynthetic components, highlighting the dynamic nature of protein turnover and quality control mechanisms in response to prolonged light exposure. The results enhance our understanding of how Crocosphaera subtropica ATCC51142 adjusts its molecular machinery in response to extended light or dark growth conditions.

Doing a double take: when transthoracic echocardiography fails for mitral valve annuloplasty ring endocarditis with Streptococcus pyogenes: a case report

BackgroundThis case highlights several complications of a late and rare presentation of culture-negative Streptococcus pyogenes endocarditis of a previously repaired mitral valve with an annuloplasty ring including recurrent cardioembolic strokes, which was initially missed on transthoracic echocardiography.Case presentationA 66-year-old Caucasian female with prior mitral valve prolapse status post mitral valve annuloplasty and left atrial appendage occlusion, followed by two strokes, presented with supraventricular tachycardia that resolved spontaneously. During an inpatient admission, she developed symptoms of another stroke, and imaging studies were suggestive of recurrent cardioembolic phenomenon. Additional workup revealed two small intra-atrial masses adherent to the mitral annuloplasty ring missed on prior evaluation for recurrent stroke. She underwent surgical repair in the setting of a chronic culture-negative infectious endocarditis with Streptococcus pyogenes and recovered well with no further cardioembolic phenomenon.ConclusionThis case serves to highlight the importance of having a higher index of suspicion in any cardiac prosthesis patient for endocarditis when presenting with symptoms such as recurrent stroke, arrhythmias, and abnormal cardiac lab work. It also demonstrates the need for appropriate imaging with transthoracic echocardiography followed by transesophageal echocardiography and reviews surgical indications to diagnose and treat culture-negative endocarditis.

Tactics for Choosing Optimal Parameters of Intense Pulsed Light in Treatment of Erythematotelangiectatic Subtype of Rosacea

INTRODUCTION: There exist several approaches to treatment of rosacea: systemic, external or complex therapy. Many practitioners note the effectiveness of using intense pulsed light in treatment of rosacea acne. Along with hardware techniques, azelaic acid-based gel is actively used in treatment. Despite the growing popularity of phototherapy, there is insufficient scientific literature on the study of optimal parameters of intense pulsed light for patients using azelaic acid. AIM: To describe the experience of application of a combination of intense pulsed light and azelaic acid in erythematotelangiectatic subtype of rosacea. A clinical case of a 52-year-old female patient with severe erythematotelangiectatic rosacea. Phototherapy was conducted in a course of 7 procedures with an interval of 3 weeks; azelaic-based gel was prescribed twice a day for 5 months, sunscreen cream with protection factor 50 for daily use. For the first procedure, a filter with 640 nm wave length was used, fluence 22 J/cm2, pulse duration 3.5 ms, number of subpulses — 3; filter with 590 n wavelength, fluence 22 J/cm2, pulse duration 3.5 ms, number of subpulses — 3; filter with 560 nm wavelength, fluence 20 J/cm2, pulse duration 3.5 ms, number of subpulses — 3; filter with 515 nm wavelength, fluence 16 J/cm2, pulse duration 3.5 ms, number of subpulses — 3. After 3 weeks, a second phototherapy procedure was conducted according to the same protocol. In the third procedure, the energy flow on each filter was increased by 1 J, pulse duration and number of subpulses did not change. On examination in 3 weeks, there was a reduction of the number of small and large telangiectasias, significant reduction of redness, no disturbing subjective sensations. In the subsequent procedures it was decided not to increase the energy flow on filters to avoid recurrent undesired phenomena. CONCLUSION: Clinical observation demonstrated the effectiveness of using a combination of intense pulsed light and azelaic acid in erythematotelangiectatic rosacea when selecting the maximum permissible parameters of phototherapy. When treating with intense pulsed light it is permissible to increase the energy flow by 1 J/cm2–2 J/cm2 on condition of normal tolerance. In case edema and hyperemia are present for more than 3 days, it is necessary to reduce the energy flow.

Echocardiographic predictors and associated outcomes of multiple vegetations in infective endocarditis: A pilot study.

Infective endocarditis (IE) is a life-threatening infection with an annual mortality of 40%. Embolic events reported in up to 80% of patients. Vegetations of > 10 mm size are associated with increased embolic events and poor prognosis. There is a paucity of literature on the association of multiple vegetations with outcome. To study the echocardiographic (ECHO) features and outcomes associated with the presence of multiple vegetations. In this retrospective, single-center, cohort study patients diagnosed with IE were recruited from June 2017 to June 2019. A total of 84 patients were diagnosed to have IE, of whom 67 with vegetation were identified. Baseline demographic, clinical, laboratory, and ECHO parameters were reviewed. Outcomes that were studied included recurrent admission, embolic phenomenon, and mortality. Twenty-three (34%) patients were noted to have multiple vegetations, 13 (56.5%) were male and 10 (43.5%) were female. The mean age of these patients was 50. Eight (35%) had a prior episode of IE. ECHO features of moderate to severe valvular regurgitation [odds ratio (OR) = 4], presence of pacemaker lead (OR = 4.8), impaired left ventricle (LV) relaxation (OR = 4), and elevated pulmonary artery systolic pressure (PASP) (OR = 2.2) are associated with higher odds of multiple vegetations. Of these moderate to severe valvular regurgitation (P = 0.028), pacemaker lead (P = 0.039) and impaired relaxation (P = 0.028) were statistically significant. These patients were noted to have an increased association of recurrent admissions (OR = 3.6), recurrent bacteremia (OR = 2.4), embolic phenomenon (OR = 2.5), intensive care unit stay (OR = 2.8), hypotension (OR = 2.1), surgical intervention (OR = 2.8) and device removal (OR = 4.8). Of this device removal (P = 0.039) and recurrent admissions (P = 0.017) were statistically significant. This study highlights the associations of ECHO predictors and outcomes in patients with IE having multiple vegetations. ECHO features of moderate to severe regurgitation, presence of pacemaker lead, impaired LV relaxation, and elevated PASP and outcomes including recurrent admissions and device removal were found to be associated with multiple vegetations.

Ammonia-induced constraints on butyrate degradation in anaerobic digestion: Impact of ammonia levels and pH conditions, and recovery behaviour

The accumulation of butyrate is a recurrent phenomenon in anaerobic digesters utilizing animal manure as the primary feedstock. Despite its prevalence, the factors governing the anaerobic degradation of butyrate remain inadequately explored. In this study, a series of experiments were carried out under different total ammonia concentrations (TAN, 0.18–20 g N/L) and pH conditions (7.0–8.0) to investigate the inhibition of butyrate anaerobic degradation by different ammonia species (NH4+ and NH3) and to assess the recoverability following severe ammonia inhibition. The findings indicate that at pH 7.5, butyrate degradation experienced remarkable inhibition when TAN exceeded 8.0 g N/L, while no discernible impact was observed at pH 7.0–8.0 and 4.0 g TAN/L. Additionally, the lag phase for butyrate degradation extended with increasing TAN concentration. Notably, the activity of butyrate-degrading bacteria exhibited full recovery from severe ammonia inhibition (TAN 20 g N/L or NH3 779.2 mg N/L), provided prolonged adaption time was allowed. The analysis using a modified Monod inhibition model highlighted that NH4+ contributed more to inhibition than NH3 at TAN concentrations of 2.0–20.0 g N/L. Therefore, simply reducing pH levels would not adequately counteract ammonia inhibition. Implementing an extended hydraulic retention time emerges as an effective measure to reduce butyrate accumulation in anaerobic digestion systems, particularly the feedstock being nitrogen-rich materials (e.g., animal manure).

Monitoring spatiotemporal changes in urban flood vulnerability of Peninsular Malaysia from satellite nighttime light data

Urban flood vulnerability monitoring requires a large amount of socioeconomic and environmental data collected at regular time intervals. However, collecting such a large volume of data poses a significant constraint in assessing changes in flood vulnerability. This study proposed a novel method to monitor spatiotemporal changes in urban flood vulnerability from satellite nighttime light (NTL) data. Peninsular Malaysia was chosen as the research region as floods are the most devastating and recurrent phenomena in the region. The study developed a flood vulnerability index (FVI) based on socioeconomic and environmental data from a single year. This FVI was then linked to NTL data using an Adaptive neuro-fuzzy inference system (ANFIS) machine learning algorithm. The model was calibrated and validated with administrative unit scale data and subsequently used to predict FVI at a spatial resolution of 10 km for 2000–2018 using NTL data. Finally, changes in estimated FVI at different grid points were evaluated using the Mann-Kendall trend method to determine changes in flood vulnerability over time and space. Results showed a nonlinear relationship between NTL and flood vulnerability factors such as population density, Gini coefficient, and percentage of foreign nationals. The ANFIS technique performed well in estimating FVI from NTL data with a normalized root-mean-square error of 0.68 and Kling-Gupta Efficiency of 0.73. The FVI revealed a high vulnerability in the urbanized western coastal region (FVI ∼ 0.5 to 0.54), which matches well with major contributing regions to flood losses in Peninsular Malaysia. Trend assessment showed a significant increase in flood vulnerability in the study area from 2000 to 2018. The spatial distribution of the trend indicated an increase in FVI in the urbanized coastal plains, particularly in rapidly developing western and southern urban regions. The results indicate the potential of the technique in urban flood vulnerability assessment using freely available satellite NTL data.

Camelus knoblochi genome reveals the complex evolutionary history of Old World camels

Extant Old World camels (genus Camelus) contributed to the economic and cultural exchanges between the East and West for thousands of years.1,2 Although many remains have been unearthed,3,4,5 we know neither whether the prevalent hybridization observed between extant Camelus species2,6,7 also occurred between extinct lineages and the ancestors of extant Camelus species nor why some populations became extinct while others survived. To investigate these questions, we generated paleogenomic and stable isotope data from an extinct two-humped camel species, Camelus knoblochi. We find that in the mitochondrial phylogeny, all C.knoblochi form a paraphyletic group that nests within the diversity of modern, wild two-humped camels (Camelus ferus). In contrast, they are clearly distinguished from both wild and domesticated (Camelus bactrianus) two-humped camels on the nuclear level. Moreover, the divergence pattern of the three camel species approximates a trifurcation, because the most common topology is only slightly more frequent than the two other possible topologies. This mito-nuclear phylogenetic discordance likely arose due to interspecific gene flow between all three species, suggesting that interspecific hybridization is not exclusive to modern camels but a recurrent phenomenon throughout the evolutionary history of the genus Camelus. These results suggest that the genomic complexity of Old World camels' evolutionary history is underestimated when considering data from only modern species. Finally, we find that C.knoblochi populations began declining prior to the last glacial maximum and, by integrating palaeoecological evidence and stable isotope data, suggest that this was likely due to failure to adapt to a changing environment.

Preventing Hump Recurrence in Dorsal Preservation Rhinoplasty: The Five Key Tenets

SUMMARY: Preservation rhinoplasty has re-emerged over the past decade and continues to gain traction in the rhinoplasty community. Dorsal preservation rhinoplasty (DPR), one of the tenets of preservation rhinoplasty, centers on preservation of the native osseocartilaginous joint of the dorsum, with changes instead achieved through modification of the underlying septal cartilage and surrounding bony nasal pyramid. However, one complication unique to DPR is the phenomenon of hump recurrence, where tensile forces or memory lead to a recurrent convexity of the dorsal hump. Hump recurrence is the most common complication after DPR and often requires revisionary surgery. Accordingly, strategies to reduce the incidence of hump recurrence are highly sought after. In this article, we describe the senior author’s main tenets of preventing hump recurrence in DPR, focusing on 1. Appropriate patient selection; 2. Addressing anatomic blocking points; 3. Adding mechanical fixation of the cartilaginous vault with suture techniques depending on the level of septal manipulation; 4. Applying a graduated approach to DPR procedural selection; and 5. Ancillary measures to control the shape of the nasal dorsum. Implementation of each of these five tenets is critical for modern rhinoplasty surgeons to reduce the incidence of hump recurrence in their preservation rhinoplasty practices.

Acknowledging and legitimizing the embarrassment: Responding to embarrassment-telling

Sharing embarrassing experiences is an ordinary and recurrent social phenomenon, and this article carries out a conversation analytic study on how embarrassment-telling is interactionally co-constructed in talk-in-interaction. It is found that embarrassment-telling is delivered as an incident that should not have happened happens by accident to the teller due to the embarrassment-teller’s unintended violation of a normative practice. In response, the co-interactant acknowledges the experience’s being embarrassing, while legitimizes the teller’s being embarrassed, thus making the response to embarrassment-telling a nuanced issue by maneuvering between affiliation and disaffiliation with the teller. Data are in Mandarin Chinese with English translation.

Deformation characteristics and reactivated failure modes of the massive Baimu ancient landslide deposit on the northern margin of the East Himalayan syntaxis

AbstractIn the Eastern Himalayan syntaxis, massive Quaternary loose deposits represent a typical product of abrupt topographic changes. Influenced by the Qinghai‐Tibet Plateau uplift and rapid river incision, the partial or complete failure of these deposits is a recurrent phenomenon in alpine‐gorge regions, posing substantial threats to major infrastructure development. Through topographic interpretation and field investigation, this study clarifies the geological features and genetic mechanisms of the Baimu ancient landslide deposit (BALD), located on the northern margin of the East Himalayan syntaxis. The surface deformation time series spanning October 2017 to December 2019 was estimated using employing multitemporal synthetic aperture radar interferometry. Then, the spatiotemporal deformation characteristics of the BALD was analysed by superposing terrain factors, and hazard division was implemented. The results indicate that high‐hazard zones are mainly distributed on high and steep free faces of the BALD. Deformation evolution and rainfall time series showed obvious correlation. Lastly, a generalized failure model is established for the BALD, which will serve as a valuable reference for disaster prevention and is applicable to the study of similar deposits in the Qinghai‐Tibet Plateau.

The Brazil current cyclonic meandering and shelf-slope water exchanges at 27°S–31°S

The Brazil Current (BC) experiences intense mesoscale activity from its origin on the northeastern Brazilian coast till it reaches the Brazil-Malvinas Confluence. The BC meandering behavior near the Cape Santa Marta (27°S – 31°S), has not been well described in the literature. In this study, in situ observations and satellite images are used to describe the BC meanders and cyclonic eddies near the cape. The results obtained from two Lowered Acoustic Doppler Current Profilers (LADCP) sections show that these structures are surface intensified but extend through the whole water column. Conductivity Temperature and Depth (CTD) profiles show evidence of coastal water trapping inside an eddy. Altimeter data show two hot spots of cyclones, one at 28.5°S and the other at 30.5°S, with an average of ∼5 and 7 eddies per year, respectively. The eddies generated on both sites have a mean lifetime of 37 days, and no significant differences were found between their surface properties. Satellite images of chlorophyll show that coastal water horizontal advection is a recurrent phenomenon in these eddies, imprinting an eddy stirring signal into their average composites. Furthermore, using Empirical Orthogonal Functions to analyze the BC flow in a mooring line, we observed that the mesoscales meanders are responsible for explaining at least 1/3 of the flow variability in this area.

Trend of Ostreopsis cf. ovata (Dinophyceae) along the Conero Riviera (northern Adriatic Sea) over two decades

ABSTRACT Harmful blooms of the toxic dinoflagellate Ostreopsis cf. ovata have been a recurrent phenomenon along the Mediterranean coasts in the last decades. Since first recorded, there has been a widespread belief that the extension of this dinoflagellate, well-known in tropical areas, to higher latitudes was due to global warming and the general rise of seawater temperature. Blooms of O. cf. ovata along the Conero Riviera (northern Adriatic Sea) occur between the end of the summer and the beginning of the autumn since 2006. The Ostreopsis cf. ovata abundances collected from its first record to today were analysed to better define the interannual trend of this phenomenon and its possible linking to certain climate change predictors. A significant increasing trend in the magnitude of Ostreopsis phenomenon was observed up to year 2012, then a stabilization at relatively low values was observed. This trend does not follow the incessant increase in water temperature observed during the last three decades in the Adriatic Sea, but rather recalls patterns seen in invasive species, although the provenience of O. cf. ovata in the Mediterranean Sea is still unresolved. Even if the Ostreopsis bloom in this area seems to slightly lessen in the last decade, Ostreopsis abundances still reach values of up to 103 cells cm−2 which could be harmful to human health.

Deciphering cometary outbursts: linking gas composition changes to trigger mechanisms

ABSTRACT Dust and gas outbursts are recurrent cometary phenomena, playing a crucial role in shaping the coma. Proposed outburst trigger mechanisms include cliff collapse, pressure pockets, and amorphous-to-crystalline phase transition of water ice; however, the underlying processes remain inadequately understood. In this study, we analyse Rosetta/ROSINA data from multiple outbursts on comet 67P/Churyumov-Gerasimenko and present the evolution of the gas composition in the comet’s coma during outburst events. We distinguish two distinct categories of cometary outbursts on the comet: water-driven events characterized by rapid (minutes to hours) changes in coma composition, and CO2-driven events displaying a slow, prolonged (hours to days) increase in highly volatile species. We tentatively associate these different gas composition patterns with different trigger mechanisms. Exposure of fresh ice due to cliff collapse leads to a notable water enhancement, while most perihelion outbursts coincide with substantial density increases of CO2. We propose that these CO2-driven events originate from subsurface gas-filled cavities, whose walls are suggested to have been sealed by earlier refreezing of CO2 migrating from warmer spots, hence increasing the cavity pressure required to burst.