Intensity Regime Research Articles

Primary Modes of Northern Hemisphere Snowfall Particle Size Distributions

Abstract A comprehensive understanding of snowfall microphysics is crucial for enhancing the accuracy of remote sensing snowfall retrievals. However, variations in regional and seasonal snow particle size distributions (PSDs) contribute substantial uncertainty. Here, we examine snowfall PSDs from across the Northern Hemisphere, applying principal component analysis (PCA) to disdrometer observations with the aim of identifying dominant modes of variability across varying regional climates. The PCA revealed three empirical orthogonal functions (EOFs) that account for a combined 95% of the variability across the dataset, which are attributed to latent linear embeddings of snowfall intensity (EOF1), snowfall character (EOF2), and snowfall regime (EOF3). Examining point clusters with the highest combined EOF values reveals six distinct modes of variability [i.e., principal component (PC) groups] with unique PSD traits. These groups are then correlated with environmental factors using data from collocated vertically pointing radar, surface meteorology, and reanalysis to assist in assigning physical attributes. The first and second PC groups, linked to EOF1’s intensity embedding, are described by their PSD intercepts, snowfall rates, and reflectivity and Doppler velocity values, representing low- and high-intensity snowfall modes, respectively. The third and fourth PC groups, associated with EOF2’s character embedding, are defined by temperature, fall speed, and density, indicative of cold, fluffy snowfall and warm, dense snowfall, respectively. The fifth and sixth PC groups, related to EOF3’s regime embedding, are distinguished by their PSD slope, snowfall rate, and reflectivity profiles, signifying shallow, weak convective systems with small particles and deep, stratiform snowfall events with large aggregates, respectively. Significance Statement This research enhances our understanding of varying snow particle size distributions in the Northern Hemisphere, offering valuable new insights for improving future remote sensing–based snowfall retrieval algorithms. Using a statistical technique called principal component analysis, we found that 95% of the variability in observed snowfall could be explained by three primary features: how intense the snowfall is, how dense the particles are, and the depth of the storm. We identified six unique snowfall groups, each with its own set of traits, such as the snow being light and fluffy, or heavy and packed. By linking these traits to external environmental observations, we can better understand the driving physical mechanisms within each group.

Optimization of sandstone processing waste, electric arc furnace slag, and fly ash-based ternary blended eco-friendly geopolymers.

Over the years, ordinary Portland cement (OPC) has been used to meet growing demands of land and housing facilities arising out of population overburdens. It is well documented that OPCs, besides their outstanding qualities as building materials, are also significant contributors to global greenhouse gases (GHG). Consequently, recent years have noticed an emerging interest in the search for alternatives to Portland cement-based binders. Geopolymers are well-suited to serve this purpose owing to their superior attributes and low CO2 emissions compared to conventional cement. Still, the industrialization of geopolymers has not reached a meaningful value due to the prevailing fundamental barriers involving the requirement of corrosive environments and intensive heat-curing regimes in post-fabrication processes. The current study investigates the viability of using synergistic mixtures based on stone residues, pulverized ash, and steel slags in fabricating geopolymer composites cured at ambient temperature with reduced ingestion of alkalis. A comprehensive assessment of the engineering, mineralogical, and microstructural characteristics was performed in terms of setting times, physico-mechanical, durability, non-destructive, and analytical tests. Further, a scaled-down approach was utilized to evaluate the feasibility of the designed composites as construction entities. The incorporation of SW (10-40%) prolonged the setting periods (~ 150min.) and abridged the engineering properties of the ternary pastes collectively by 127% due to silica coalescences. Besides, replacements of stone residues with FA (20-30%) and EAF (30-60%) improved the blend performance due to Ca and Al assimilations. All the developed composites satisfied the acclamations for OPC grade 33, CEM V class 32.5N, and OPC Type - I suggested by IS, EN, and ASTM standards, respectively, with matrices constituting CASH-CSH-NASH-(N,C)-A-S-H type gelation complexes identified by the X-ray, infrared, and electron imaging spectroscopic analysis. In addition, a cumulative deficit of about 60-90% was observed in energy and carbon footprints relative to OPCs, indicative of the binders' sustainability traits.

Using Structural Causal Modeling to Infer the Effects of Wildfire on Foothill Yellow-legged Frog Occurrence

Abstract Sierra Nevada ecosystems have been influenced by fire for millennia; however, increasing wildfire size and frequency may yield unforeseen consequences on wildlife populations and their distribution. Foothill yellow-legged frogs Rana boylii have declined in portions of their range and are considered a species of conservation concern. We surveyed streams for foothill yellow legged frogs in and near the 2021 Dixie Fire footprint using double-observer visual encounter surveys that incorporated time-to-detection methods, and used structural causal modeling to improve post-fire inference while lacking pre-fire data. We found that foothill yellow-legged frog probability of occurrence was 4.93 (95% equal-tailed interval = 0.52 – 160) times higher outside the footprint of the Dixie Fire than within it, though probability of occurrence was generally low within our sampling frame (ψunburned = 0.21 [0.08 – 0.49]; ψburned = 0.05 [0.002 – 0.28]). Measured environmental characteristics, however, were similar within and outside the fire footprint, and observed occupancy patterns might reflect the recent historical distribution of the frogs. Our study emphasizes the importance of site-specific pre-disturbance data when attempting to evaluate the causal effects of disturbances on wildlife. Although it remains to be seen how this species will fare in an increasingly frequent and intense fire regime, foothill yellow-legged frogs may tolerate some level of fire disturbance.

Life Cycle Cost Analysis and Deterioration Patterns of Limestone Paving

Stone is a durable and high-performance paving material in standard and in intensive service regimes. Stone is thus a preferable material for sidewalk and promenade paving under intensive service regimes, such as touristic promenades and historic sites. Recent studies on the weathering and degradation of stones in buildings have revealed differing analytical approaches among geologists, geo-engineers, and civil engineers. The present research aims to develop a structured analytical–empirical methodology for the assessment of stone pedestrian pavements’ life cycle and life cycle costs. This study presents an integrated methodology that combines diagnostic field surveys, core laboratory tests, and the characterization of deterioration patterns. This approach allows for evaluating how faulty construction methods impact the durability and degradation of natural stone pedestrian pavements. It also assesses their effect on the pavement’s life cycle and associated costs. The diagnostic field survey concentrates on specific construction details, including: (a) Cracks in the paving stones. (b) Peeling of stone layers. (c) Subsidence and cracking at the paving edges. (d) Cracking of filler materials in joints between stone slabs. The laboratory tests focus on five core physical properties for the stone deterioration: (1) apparent density, (2) Water absorption, (3) Compressive strength, (4) Flexural strength, and (5) Abrasion resistance. This study proposes linear and exponential patterns for deterioration. A case study carried out on a Capernaum promenade revealed excessive deterioration patterns caused by the poor core properties of the paving stone and defective construction. The consequences of excessive deterioration on life cycle costs result in additional expenses of 73%, indicating a reduction in the life cycle. The novelty of this research lies in developing and delivering an integrated methodology that enables the assessment of how defective construction methods impact the durability, deterioration, life cycle, and life cycle costs of natural stone pedestrian pavements.

Midge Paleo-Communities (Diptera Chironomidae) as Indicators of Flood Regime Variations in a High-Mountain Lake (Italian Western Alps): Implications for Global Change

Sediments of alpine lakes serve as crucial records that reveal the history of lacustrine basins, offering valuable insights into the effects of global changes. One significant effect is the variation in rainfall regimes, which can substantially influence nutrient loads and sedimentation rates in lacustrine ecosystems, thereby playing a pivotal role in shaping biotic communities. In this study, we analyze subfossil chironomid assemblages within a sediment core from an alpine lake (western Italian Alps) to investigate the effects of rainfall and flood regime variations over the past 1200 years. Sediment characterization results highlight changes in sediment textures and C/N ratio values, indicating phases of major material influx from the surrounding landscape into the lake basin. These influxes are likely associated with intense flooding events linked to heavy rainfall periods over time. Flooding events are reflected in changes in chironomid assemblages, which in our samples are primarily related to variations in sediment texture and nutrient loads from the surrounding landscape. Increased abundances of certain taxa (i.e., Brillia, Chaetocladius, Cricotopus, Psectrocladius, Cricotopus/Orthocladius Parorthocladius) may be linked to higher organic matter and vegetation inputs from the surrounding landscape. Biodiversity decreased during certain periods along the core profile due to intense flood regimes and extreme events. These results contribute to our understanding of alpine lake system dynamics, particularly those associated with intense flooding events, which are still understudied.

Past and future impacts of marine heatwaves on small-scale fisheries in Baja California, Mexico

Marine heatwaves are globally occurring events that can negatively impact fisheries, but their impacts on small-scale operations remain understudied. We investigate the historical and future impacts of marine heatwaves on small-scale fisheries operating along a biogeographic transition zone in the Baja California Peninsula, Mexico. We estimate the impacts of the most intense marine heatwave regime on record on fisheries production of 43 economic units operating in a system of 55 Territorial Use-Rights for Fisheries. During this regime, aggregate landings in the lobster, sea urchin, and sea cucumber fisheries decreased between 15 and 58%. Most operations (56%) presented large reductions in landings, whose losses more than outweigh the small increase detected for the other 44%. Notably, impacts were larger for fisheries operating near an equatorward biogeographic break, and for operations in areas of high historical environmental variation and low historical variation in fisheries production. Climate models predict an increase in the frequency and intensity of exposure to marine heatwaves for all fisheries, but the change in frequency and intensity will be greater for those in the north. In the face of extreme environmental shocks such as marine heatwaves, small-scale fisheries operating near biogeographic transition zones are among the most vulnerable.

Analyzing the temporal response mechanisms of the vascular bundles formation of grafted cucumber to different light intensity modes: A joint transcriptomic and metabolomic approach

In plant grafting, the reconnection of vascular bundles between the rootstock and scion not only establishes functional xylem and phloem connections, but also signifies the completion of graft healing. In our previous studies focused on early-stage morphology and physiology of grafted seedlings, we have demonstrated that utilizing light intensities of 50-100-150 μmol/(m2·s) during days 1-3, 4-6, and 7-9 optimizes cucumber/pumpkin graft healing. To further explore the underlying mechanisms, we investigate light intensity regimes: 50-100-100 μmol/(m2·s) and 50-100-150 μmol/(m2·s) during the same time frames (days 1-3, 4-6, and 7-9 after grafting), denoted as CK and T treatments. Initially, we observe histological characteristics of vascular bundle formation under these conditions, followed by the analyses of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), glutathione peroxidase (GSH-Px) enzyme activities, ascorbic acid (AsA) content in the antioxidant system, and the sequencing of transcriptome and metabolome. It is found that grafted seedlings under the T treatment achieve faster vascular bundle reconnection and shorter healing process compared to those under the CK treatment. Enzyme activities (POD, SOD, GSH-Px) increase over time under both light regimes, while CAT activity and AsA content decrease. Notably, by the 9th day, the T treatment (T9d) exhibits higher SOD, POD and CAT activities than the CK treatment (CK9d). Our findings indicate that increasing light intensity during the days 7-9 after grafting can mitigate oxidative damage at the grafting site and benefit vascular bundle reconnection. Transcriptome and metabolome analyses show the up-regulations of Cinnamaldehyde in the phenylpropanoid biosynthesis pathway, the PHGDH gene and L-Homocysteine in the cysteine and methionine metabolism pathway under T treatment in the days 7-9 after grafting. These enhance the antioxidant enzyme activities and reduce the oxidative damage to the grafting site. Additionally, GAE-related genes, and metabolites D-Xylose and Undecaprenyl phosphatealpha-L-Ara4FN in the amino sugar and nucleotide sugar metabolism pathways are also up-regulated under T treatment. The ethylene responsive factor (ERF) transcription factor CsaRAP2.3 positively regulates Undecaprenyl phosphatealpha-L-Ara4FN expression, promoting cell wall synthesis and therefore accelerating vascular bundle reconnection. In summary, during the vascular bundle formation period of cucumber graft healing, both light intensity modes coordinate regulation of phenylpropanoid biosynthesis, cysteine and methionine metabolism, amino sugar and nucleoside sugar metabolism, and ERF transcription factors, promoting graft healing from both stress resistance and cell wall synthesis. Furthermore, building upon the light intensity applied during the callus formation phase, increasing the light intensity during the vascular bundle formation period can significantly enhance cell wall synthesis, thus expediting the graft healing process. Nonetheless, the generalizability of these research findings to other grafting techniques and species requires further investigation.

Study of ablation and shock generation across three orders of magnitude of laser intensity with 100 ps laser pulses

The laser ablation and subsequent shock generation in solid targets plays an important role in a variety of research topics from equation of state models for materials to inertial confinement fusion. One of the long-standing issues is the knowledge of ablation depth in the picosecond time regime. We report on a direct technique for determining the ablation depth in aluminum using x-ray diffraction data from Linac Coherent Light Source at the Stanford Linear Accelerator Center. This technique gives a direct measurement of the shock wave propagation in the bulk target, enabling an ability to discern early timescale physics from late timescale effects not available in postmortem analysis. We find that the ablation depths only vary by 0.2 μm across three orders of magnitude of laser intensity, while the pressure increased by a factor of 10 following a square root dependence on laser pulse energy. We further observe that the ablation depth in this intensity range (1011–1013 W/cm2 in intensity, corresponding to 0.8–80 J/cm2 in fluence) cannot be modeled by a universal scaling law, given the complexity of the mechanisms governing laser ablation in this intensity regime.

Woodhouse-sakati syndrome with no reportable MRI findings: a case report

BackgroundWoodhouse-Sakati Syndrome (WSS) is a rare autosomal recessive condition caused by biallelic pathogenic variants in the DCAF17 gene, with fewer than 200 cases reported in the literature. Symptoms first emerge in middle-late adolescence with a spectrum of hypogonadal and progressive neurological features.Case presentationWe present a case of WSS with no reportable T2-weighted, apparent diffusion coefficient mapping and susceptibility weighted MRI findings. This differs from cases reported in the current literature. Our patient developed abnormal movements in both legs, clumsiness of the hands, dysarthria, and swallowing difficulties. Moreover, she presented with alopecia manifesting as frontal and temporal balding, severe dystonia with painful dystonic spasms primarily in the left upper limb, as well as primary amenorrhea. She was not independently ambulatory on presentation, requiring wheelchair assistance. Genetic testing, the crucial test for a definitive diagnosis, was undertaken in Qatar and confirmed WSS. Treatment provided includes botulinum toxin injections and deep brain stimulation, providing better dystonia control, with progress in walking and strength exercises, and overall remarkable improvement. Intensive neurorehabilitation regimes were also deployed from admission, including physiotherapy, occupational therapy and speech and language therapy.ConclusionThis case adds to the current literature on WSS manifestations, with all previously reported cases having positive MRI findings, unlike our case.

Effect of dephasing on modulation transfer in potassium

In this work, experimental studies on the effect of dephasing on modulation transfer are reported. Here Potassium D1 transition, i.e., 39K 4S1/2(F) → 4P1/2(F/), is used as the medium. The 4 S→4P connection is modified by introducing two independent lasers. The separation between ground hyperfine states 4S1/2(F = 2,1) is almost half of Doppler width (~ 815 MHz). Hence, the two-level connections satisfied by respective lasers are overlapping in nature. In such cases, the existing optical pumping for particular F = 1, 2→ F/ channel influences each other. Further, the D1 transition itself is an open transition, i.e., it does not have any cyclic decay route. Hence, decay from each of the F/=2,1 states can also influence the population in the other F/state. Our pump-probe spectroscopy results clearly show the presence of Four Wave Mixing due to degenerate two-level and Vee (V) coupling, Electromagnetically Induced Transparency (EIT) signals due to single Lambda (Λ) and Double Λ connections. We have studied these signals as a function of dephasing, which is mainly contributed by transit time broadening for two different regimes of pump laser intensities: (i) below and (ii) above saturation intensity level of 4S1/2(F) → 4P1/2(F/) transition. The pump laser is current modulated, and phase-sensitive detection is performed on the probe transmission to study modulation transfer under different values of coherent dephasing. For this purpose, the beam size of the pump laser is varied systematically. This study provides a scope to explore the modulation transfer as a function of transit time broadening, and it may find applications in photonics technology where potassium vapor is used as a medium.

Tracing 40,000 years of vegetation change in the Baetic-Rifan biodiversity hotspot

This study presents a 40,000-year-old pollen record from Los Tollos Lake in the Baetic-Rifan region of southernmost Spain. The data offer insights into the past ecosystems of a current biodiversity hotspot situated at the ecotone between the Atlantic and the Mediterranean. This new sequence encompasses Mediterranean and Ibero-North African sclerophylls, broad-leaf trees, conifers, and Tertiary relicts. The full-glacial abundance of mesothermophytes, particularly oaks, is among the highest recorded for the European Quaternary. Notably, the presence of ecologically significant pollen taxa, which are poorly dispersed and currently occur outside the study area, suggests that this biodiversity hotspot was more extensive in the Pleistocene. During the period of c. 40.8–36.5 ka, three Artemisia maxima at 40.6, 38.9, and 36.9 ka coincide with decreases in Quercus, indicating the spread of steppes in response to the abrupt coolings of the GS10, GS9 (HS4), and GS8 events. Similarly, increases in Quercus around 41, 40, and 37.2–38.3 ka parallel the GI10, GI9, and GI8 warm events. A forested period from 36.5–32 ka includes oak expansions during the GI7 and GI6 interstadials. From 32 to 19.2 ka, more xerophytic vegetation is observed, including the HS3, GS5-GS3, HS2, and GS2.1b-c cold spells, although the correlation with vegetation changes is not synchronous. As early as approximately 21 ka, Artemisia definitively declines, while the region was reforesting, likely due to the presence of stationary populations of broadleaf trees and conifers in the southern Baetic mountains. From approximately 12 ka onwards, the highest values of angiosperm trees are recorded, with oaks dominating throughout most of the Holocene. The pollen record and the correlation with marine records suggest a more intense hydrological regime during the first half of the Holocene, but there is also archaeobotanical evidence for human activity during the second half, resulting in a more open landscape, making it difficult to discriminate the impact of each factor. Some abrupt aridity events during the Holocene coincide with small variations in tree cover, particularly at 9.2, 8.2, 6.8, 5.5–4.8, 4.2, and 2.8 ka. Since the Neolithic and during the metallurgic stages, forest species, especially broad-leaf trees, experienced range retraction accompanied by population extinctions. The region's plant communities have been subject to fire regimes since the Pleistocene, seemingly dependent on the available tree biomass.

EVALUATION OF THE GLYCOREGULATION EFFICACY BEFORE AND AFTER TREATMENT WITH INSULIN DEGLUDEC IN PATIENTS WITH TYPE 2 DIABETES MELLITUS IN THE REPUBLIC OF NORTH MACEDONIA

Patients with type 2 diabetes mellitus (T2DM) who have unsatisfactory glycoregulation with concurrent use of basal insulin and oral hypoglycemics, should be switched to a more intensive therapy regime. To evaluate the efficacy of newly available insulin degludec 70/insulin aspart 30 (IDegAsp), we retrospectively analyzed glycoregulation in 131 patients with T2DM treated with this insulin. All 131 patients were with unsatisfactory glycoregulations, and were switched to IDegAsp from other insulins (except basal-bolus insulin regimen). After a mean period of 11.75±5 months of the treatment with IDegAsp, we found statistically significant improvement in fasting and postprandial glucose levels, and HbA1c (12.5±4.4 vs. 8.8±3.9mmol/l, 13.2±4.6 vs. 9.6±4.1mmol/l, 9.7±1.8 vs. 8.1±1.6%, p<0.01, respectively). The total average daily dose of insulin units (IU) was the same, and there weren’t statistically significant differences in the frequency of hypoglycaemia (p<0.05). From the results, we can conclude that patients with T2DM, who switched to IDegAsp from previous antidiabetic insulin treatment (except basal-bolus insulin regimen) had improved glycaemic control without increased insulin units, and without higher risk for hypoglycemia.

Silvicultural regime shapes understory functional structure in European forests

Abstract Managing forests to sustain their diversity and functioning is a major challenge in a changing world. Despite the key role of understory vegetation in driving forest biodiversity, regeneration and functioning, few studies address the functional dimensions of understory vegetation response to silvicultural management. We assessed the influence of the silvicultural regimes on the functional diversity and redundancy of European forest understory. We gathered vascular plant abundance data from more than 2000 plots in European forests, each associated with one out of the five most widespread silvicultural regimes. We used generalized linear mixed models to assess the effect of different silvicultural regimes on understory functional diversity (Rao's quadratic entropy) and functional redundancy, while accounting for climate and soil conditions, and explored the reciprocal relationship between three diversity components (functional diversity, redundancy and dominance) across silvicultural regimes through a ternary diversity diagram. Intensive silvicultural regimes are associated with a decrease in functional diversity and an increase in functional redundancy, compared with unmanaged conditions. This means that although intensive management may buffer communities' functions against species or functional losses, it also limits the range of understory response to environmental changes. Policy implications. Different silvicultural regimes influence different facets of understory functional features. While unmanaged forests can be used as a reference to design silvicultural practices in compliance with biodiversity conservation targets, different silvicultural options should be balanced at landscape scale to sustain the multiple forest functions that human societies are increasingly demanding.

Harmful and Potentially Harmful Constituents Analysis of North American ENDS

Summary The objective of this study was to create a North American e-cigarette, or electronic nicotine delivery system (ENDS), market map representative of the 2020 and 2021 commercial market for analysis of harmful and potentially harmful constituents (HPHCs) and other chemicals in aerosol. The study consisted of 14 brands (seven closed pod-based, four open (refillable) pod-based, two cigalike, one disposable) and analyzed multiple e-liquid formulations per brand with varying labelled nicotine concentrations and flavors, equating to 35 unique tested ENDS. Aerosol was generated using two puffing regimes (ISO 27068 and intense) and analyzed for primary constituents, metals, carbonyls, and glycidol in a head-to-head comparison in the same testing laboratory. Nicotine yields per puff ranged from 0.045 mg/puff for the lowest yielding ENDS under the ISO 27068 puffing regime to 1.11 mg/puff for the highest yielding ENDS under intense puffing conditions. For carbonyls, all ENDS generated quantifiable amounts of acetaldehyde, acrolein, and formaldehyde in collected aerosol, irrespective of puffing regime, with an increase in yields observed under intense puffing compared to ISO 27068 puffing for the majority of tested ENDS. For metals, the ENDS aerosol yielded nickel (Ni) ranging from below limits of detection (BLOD) to >30 ng/puff, while quantifiable levels of chromium (Cr), copper (Cu), and lead (Pb) were only associated with select ENDS. All tested ENDS aerosol contained quantifiable glycidol ranging from 0.003 to >1.00 µg/puff for ISO 20768 and 0.005 to 1.10 µg/puff for intense puffing regimes. As a category, ENDS aerosol showed significantly reduced levels of HPHCs compared to 1R6F combustible cigarette (CC) smoke on a per nicotine basis. However, there was variability among ENDS and the aerosol of some ENDS products produced increased levels of specific HPHCs (e.g., formaldehyde and nickel) compared to 1R6F CC smoke. The observed HPHC variations appear to be primarily dependent on device design. In summary, this work is one of the most comprehensive analyses of HPHCs for North American ENDS using validated analytical methods in the same test facility for a head-to-head comparison.

A synthesized field survey database of vegetation and active-layer properties for the Alaskan tundra (1972–2020)

Abstract. Studies in recent decades have shown strong evidence of physical and biological changes in the Arctic tundra, largely in response to rapid rates of warming. Given the important implications of these changes for ecosystem services, hydrology, surface energy balance, carbon budgets, and climate feedbacks, research on the trends and patterns of these changes is becoming increasingly important and can help better constrain estimates of local, regional, and global impacts as well as inform mitigation and adaptation strategies. Despite this great need, scientific understanding of tundra ecology and change remains limited, largely due to the inaccessibility of this region and less intensive studies compared to other terrestrial biomes. A synthesis of existing datasets from past field studies can make field data more accessible and open up possibilities for collaborative research as well as for investigating and informing future studies. Here, we synthesize field datasets of vegetation and active-layer properties from the Alaskan tundra, one of the most well-studied tundra regions. Given the potentially increasing intensive fire regimes in the tundra, fire history and severity attributes have been added to data points where available. The resulting database is a resource that future investigators can employ to analyze spatial and temporal patterns in soil, vegetation, and fire disturbance-related environmental variables across the Alaskan tundra. This database, titled the Synthesized Alaskan Tundra Field Database (SATFiD), can be accessed at the Oak Ridge National Laboratory Distributed Active Archive Center (ORNL DAAC) for Biogeochemical Dynamics (Chen et al., 2023: https://doi.org/10.3334/ORNLDAAC/2177).

Soil organic matter persistence in hyperhumic colluvial soils caused by palaeofires, root inputs and mineral binding

Understanding the formation of long-term persistent soil organic matter (SOM) is key to optimizing soil management and predicting the response of the terrestrial organic carbon (OC) pool to climate change, yet our knowledge of the soil-type dependent weight of different stabilization pathways (e.g., recalcitrance and mineral binding) is fragmentary. Owing to their stratigraphy, the exceptionally SOM-rich (up to 2 m of mineral soil with >5% OC) colluvial slope deposits of Atlantic Europe (Haplic Umbrisol [colluvic/hyperhumic]) are archives of palaeo-environmental conditions including SOM formation pathways. The objective of this study was to determine how the different drivers of persistent SOM formation influenced the formation of these organic-rich soils. For this purpose, we use Holocene (∼9000 yrs) molecular composition records obtained from pyrolysis-GC–MS (Py-GC–MS) and thermally assisted hydrolysis and methylation (THM-GC–MS). The results emphasize three pathways to stability (i.e., persistence on millennial timescales): 1) palaeofires that generated recalcitrant pyrogenic SOM, 2) release of root-derived aliphatic macromolecules (suberin-like SOM), and 3) formation of microbial necromass. Pathways 1 and 2 are controlled by land use: Pathway 1 was relatively important under intense anthropogenic fire regimes and pyrophytic shrubland expansion; Pathway 2 was stimulated during early forest phases and under pasture conditions, when past societies focused vegetation management on grazing instead of fire; Pathway 3 was controlled by binding with aluminium-dominated mineral phases. However, we found indications that Pathway 2 (suberin input and preservation) relied partially on sorptive preservation as well. Aided by structured equation modeling (SEM), we show that the formation of persistent SOM pools was driven by balanced weights of i) microbial vs. plant-derived SOM and ii) intrinsic chemical properties of SOM (recalcitrance continuum) vs. mineral binding/occlusion, which varied in keeping with interactions between past land use, topography and vegetation. These findings are inconsistent with the prevalent paradigm of persistent SOM formation by sorptive/occlusive preservation of microbial necromass alone.

RcOST1L phosphorylates RcPIF4 for proteasomal degradation to promote flowering in rose.

Flowering is a vital agronomic trait that determines the economic value of most ornamental plants. The flowering time of rose (Rosa spp.) is photoperiod insensitive and is thought to be tightly controlled by light intensity, although the detailed molecular mechanism remains unclear. Here, we showed that rose plants flower later under low-light (LL) intensity than underhigh-light (HL) intensity, which is mainly related to the stability of PHYTOCHROME-INTERACTING FACTORs (RcPIFs) mediated by OPEN STOMATA 1-Like (RcOST1L) under different light intensity regimes. We determined that HL conditions trigger the rapid phosphorylation of RcPIFs before their degradation. A yeast two-hybrid screen identified the kinase RcOST1L as interacting with RcPIF4. Moreover, RcOST1L positively regulated rose flowering and directly phosphorylated RcPIF4 on serine 198 to promote its degradation under HL conditions. Additionally, phytochrome B (RcphyB) enhanced RcOST1L-mediated phosphorylation of RcPIF4 via interacting with the active phyB-binding motif. RcphyB was activated upon HL and recruited RcOST1L to facilitate its nuclear accumulation, in turn leading to decreased stability of RcPIF4 and flowering acceleration. Our findings illustrate how RcPIF abundance safeguards proper rose flowering under different light intensities, thus uncovering the essential role of RcOST1L in the RcphyB-RcPIF4 module in flowering.

Sample path moderate deviations for shot noise processes in the high intensity regime

We study the sample-path moderate deviation principle (MDP) for shot noise processes in the high intensity regime. The shot noise processes have a renewal arrival process, non-stationary noises (with arrival-time dependent distributions) and a general shot response function of the noises. The rate function in the MDP exhibits a memory phenomenon in this asymptotic regime, which is in contrast with that in the conventional time–space scaling regime. To prove the sample-path MDP, we first establish that this is equivalent to establishing the sample-path MDP of another process that is easier to study. We prove its finite-dimensional MDP and then establish the exponential tightness under the Skorohod J1 topology. This results in the sample-path MDP in D under the Skorohod J1 topology with a rate function that is derived from the rate function in the finite-dimensional MDP using the tools of reproducing kernel Hilbert space. In the proofs, because of the non-stationarity of shot noise process, we establish a new exponential maximal inequality and use it to prove exponential tightness and the aforementioned equivalence.

Shining light on diurnal variation of non‐photochemical quenching: Impact of gradual light intensity patterns on short‐term NPQ over a day

AbstractMaximal sunlight intensity varies diurnally due to the earth's rotation. Whether this slow diurnal pattern influences the photoprotective capacity of plants throughout the day is unknown. We investigated diurnal variation in NPQ, along with NPQ capacity, induction, and relaxation kinetics after transitions to high light, in tomato plants grown under diurnal parabolic (DP) or constant (DC) light intensity regimes. DP light intensity peaked at midday (470 μmol m‐2 s‐1) while DC stayed constant at 300 μmol m‐2 s‐1 at a similar 12‐hour photoperiod and daily light integral. NPQs were higher in the morning and afternoon at lower light intensities in DP compared to DC, except shortly after dawn. NPQ capacity increased from midday to the end of the day, with higher values in DP than in DC. At high light ΦPSII did not vary throughout the day, while ΦNPQ varied consistently with NPQ capacity. Reduced ΦNO suggested less susceptibility to photodamage at the end of the day. NPQ induction was faster at midday than at the start of the day and in DC than in DP, with overshoot occurring in the morning and midday but not at the end of the day. NPQ relaxation was faster in DP than in DC. The xanthophyll de‐epoxidation state and reduced demand for photochemistry could not explain the observed diurnal variations in photoprotective capacity. In conclusion, this study showed diurnal variation in regulated photoprotective capacity at moderate growth light intensity, which was not explained by instantaneous light intensity or increasing photoinhibition over the day and was influenced by acclimation to constant light intensity.

Cytotoxic impact of nicotine products on periodontal ligament cells

ObjectivesThe primary objective of this in vitro experiment was an assessment of proliferative capacity, metabolic activity, and potential cellular detriment of human periodontal ligament cells (hPDL) exposed to cigarette smoke (CS), electronic cigarette vapor (eCV), and heated tobacco product aerosol (HTP), or air (control).Materials and methodsUsing a CAD/CAM-designed exposition chamber, hPDL were exposed to CS, eCV, HTP, or air (control) based on the Health Canada Intense Smoking Regime. Cell proliferation, metabolic activity, and cellular detriment were assessed at various time points.ResultsCompared to the control, hPDL exposed to CS exhibited significantly decreased cell numbers at all time points. HTP exposure led to reduced cell numbers 48 h and 72 h post-exposure, while eCV-exposed cells showed no significant decrease. The metabolic activity of eCV-treated hPDL was slightly reduced at 7 h but recovered at 24 h and 48 h. In contrast, CS-treated cells exhibited significantly decreased metabolic activity at 24 h and 48 h, and HTP-exposed cells showed a significant decrease after 48 h. Flow cytometry indicated both apoptotic and necrotic cell death following CS exposure, with necrotic cell death being more pronounced.ConclusionseCV and HTP demonstrated comparatively reduced detrimental effects on hPDL compared to CS.Clinical relevance: The findings suggest that conventional cigarette smoke poses a substantial risk to periodontal health by significantly impairing cell proliferation and metabolic activity. However, alternatives such as eCV and HTP may offer a comparatively reduced risk.