Seasonal Modulation Research Articles

Confounding Effect of Undergraduate Semester-Driven "Academic" Internet Searches on the Ability to Detect True Disease Seasonality in Google Trends Data: Fourier Filter Method Development and Demonstration.

Internet search volume for medical information, as tracked by Google Trends, has been used to demonstrate unexpected seasonality in the symptom burden of a variety of medical conditions. However, when more technical medical language is used (eg, diagnoses), we believe that this technique is confounded by the cyclic, school year-driven internet search patterns of health care students. This study aimed to (1) demonstrate that artificial "academic cycling" of Google Trends' search volume is present in many health care terms, (2) demonstrate how signal processing techniques can be used to filter academic cycling out of Google Trends data, and (3) apply this filtering technique to some clinically relevant examples. We obtained the Google Trends search volume data for a variety of academic terms demonstrating strong academic cycling and used a Fourier analysis technique to (1) identify the frequency domain fingerprint of this modulating pattern in one particularly strong example, and (2) filter that pattern out of the original data. After this illustrative example, we then applied the same filtering technique to internet searches for information on 3 medical conditions believed to have true seasonal modulation (myocardial infarction, hypertension, and depression), and all bacterial genus terms within a common medical microbiology textbook. Academic cycling explains much of the seasonal variation in internet search volume for many technically oriented search terms, including the bacterial genus term ["Staphylococcus"], for which academic cycling explained 73.8% of the variability in search volume (using the squared Spearman rank correlation coefficient, P<.001). Of the 56 bacterial genus terms examined, 6 displayed sufficiently strong seasonality to warrant further examination post filtering. This included (1) ["Aeromonas" + "Plesiomonas"] (nosocomial infections that were searched for more frequently during the summer), (2) ["Ehrlichia"] (a tick-borne pathogen that was searched for more frequently during late spring), (3) ["Moraxella"] and ["Haemophilus"] (respiratory infections that were searched for more frequently during late winter), (4) ["Legionella"] (searched for more frequently during midsummer), and (5) ["Vibrio"] (which spiked for 2 months during midsummer). The terms ["myocardial infarction"] and ["hypertension"] lacked any obvious seasonal cycling after filtering, whereas ["depression"] maintained an annual cycling pattern. Although it is reasonable to search for seasonal modulation of medical conditions using Google Trends' internet search volume and lay-appropriate search terms, the variation in more technical search terms may be driven by health care students whose search frequency varies with the academic school year. When this is the case, using Fourier analysis to filter out academic cycling is a potential means to establish whether additional seasonality is present.

Low-energy signals from the formation of dark-matter–nucleus bound states

Dark matter particles may bind with nuclei if there exists an attractive force of sufficient strength. We show that a dark photon mediator of mass $\ensuremath{\sim}(10--100)\text{ }\text{ }\mathrm{MeV}$ that kinetically mixes with Standard Model electromagnetism at the level of $\ensuremath{\sim}{10}^{\ensuremath{-}3}$ generates keV-scale binding energies between dark matter and heavy elements, while forbidding the ability to bind with light elements. In underground direct detection experiments, the formation of such bound states liberates keV-scale energy in the form of electrons and photons, giving rise to monoenergetic electronic signals with a time structure that may contain daily and seasonal modulations. We show that data from liquid-xenon detectors provides exquisite sensitivity to this scenario, constraining the galactic abundance of such dark particles to be at most $\ensuremath{\sim}{10}^{\ensuremath{-}18}--{10}^{\ensuremath{-}12}$ of the galactic dark-matter density for masses spanning $\ensuremath{\sim}(1--{10}^{5})\text{ }\text{ }\mathrm{GeV}$. However, an exponentially small fractional abundance of these dark particles is enough to explain the observed electron recoil excess at XENON1T.

Seasonal terrestrial water load modulation of seismicity at the southeastern margin of the Tibetan Plateau constrained by GNSS and GRACE data

SUMMARY The seasonal terrestrial water load modulation of seismicity is an important phenomenon to understand the mechanism behind earthquake triggering and nucleation. The presence of high-level seismicity and large seasonal water load amplitudes at the southeastern margin of the Tibetan Plateau provides a natural experimental environment for studying the modulation mechanism. The spatiotemporal distribution of the water load was inverted using Global Navigation Satellite System (GNSS) and Gravity Recovery and Climate Experiment (GRACE) data, and an earthquake catalogue (M ≥ 2.5) was declustered to obtain the background seismicity using the Epidemic Type Aftershock Sequences (ETAS) model. The Multichannel Singular-Spectrum Analysis (M-SSA) is adopted to the time-series of monthly averaged terrestrial water load and background seismicity rates, and the results show 1- and 2-yr periodicities in the seismicity rates and water load. The 1-yr periodicity in the seismicity rate is correlated with the rate of change of the monthly averaged water load. To evaluate the seasonal principal stress perturbations on the tectonic background stress orientations, the stress changes caused by the seasonal water load changes are projected onto the tectonic background stress field orientations constraining by 8 yr of earthquake focal mechanism solutions. The results show that the largest change of the seasonal principal stress perturbations is about 16 kPa. The number of excess earthquakes is evaluated with the background seismicity rates for discrete stress intervals. The results indicate a ∼10 per cent increase in the seismicity rates that correlate with the rates of the minimum and mean principal stress perturbations. The results above can be explained by the model of harmonic stress perturbations on rate-and-state fault. Based on this model, the nucleation period of the seasonal seismicity should be less than 1 yr at the southeastern margin of the Tibetan Plateau.

A high-resolution planetary boundary layer height seasonal climatology from GNSS radio occultations

We present a new seasonal planetary boundary layer height (PBLH) climatology product derived from 14 years of Global Navigation Satellite System radio occultation (GNSS-RO) data from multiple missions including COSMIC, TerraSAR-X, KOMPSAT-5, and PAZ. PBLH estimates are derived from the minimum gradients of retrieved refractivity profiles, with a vertical resolution of ∼200 m. The climatology is obtained from occultations observed between June 2006 and December 2019, and is divided into land and ocean regimes on a 2-degree grid. We provide seasonal climatologies at 2-degree resolution as well as climatologies of diurnal cycle amplitude and phase at 5-degree resolution. The new GNSS PBLH climatology is compared to radiosonde data from the ship-based Marine ARM GPCI Investigation of Clouds (MAGIC) campaign in the subtropical northeast Pacific ocean and to previous GNSS PBLH climatology estimates. The higher spatial resolution reveals new details such as seasonal PBLH modulation due to sea ice off the coast of Antarctica. The PBLH product is the first publicly available at 2-degree resolution.

Dynamics of ENSO Phase–Locking and Its Biases in Climate Models

AbstractThe contributions of different oceanic feedbacks to the El Niño–Southern Oscillation (ENSO) phase‐locking are examined by deriving ENSO dynamics based on the recharge‐discharge framework. In observations, the significant winter preference of the ENSO peak is determined by a strong seasonal modulation of SST growth rate, which is controlled by the zonal advective and thermodynamic feedbacks. However, the majority of climate models fail to simulate ENSO phase‐locking because the contribution of zonal advective feedback to the seasonal modulation of the SST growth rate is much smaller compared to observations. The weak annual cycle of the SST‐current coupling coefficient and small annual mean of the negative climatological zonal SST gradient are two factors contributing to the weak‐biased seasonality of zonal advective feedback. Further analysis shows that the Niño3.4 SSTA has better phase‐locking performance than Niño3 SSTA in the climate models due to the better simulation of zonal advection feedback in the Niño3.4 region.

Variability of bio-optical properties in nearshore waters of the estuary and Gulf of St. Lawrence: Absorption and backscattering coefficients

The inherent optical properties and the optically significant constituents in nearshore zones of the Estuary and Gulf of St. Lawrence (EGSL), eastern Canada, were systematically investigated. Dry-mass concentrations of dissolved organic carbon (DOC), phytoplankton pigments, and suspended particulate matter (SPM) were determined together with the absorption coefficients of chromophoric dissolved organic matter, acdom; non-algal particles, anap; phytoplankton, aphy; and particulate backscattering coefficient, bbp. The sampling design allowed analysis at different spatial scales and considered some intra-regional differences in distinctive zones (subregions) of the EGSL's north shore (separated by ∼ 102 km), as well as within subregions (samples separated by ∼ 100–101 km). Temporal analysis focused on seasonal variability (sampling time separated by ∼ 101–102 days). Optical indices, such as the spectral slopes of acdom and anap, pigment ratios, mass-specific absorption and backscattering coefficients, and particulate matter fractioning (inorganic and organic) allowed a detailed characterization of the dissolved organic matter pool and provided useful information about particulate matter assemblages. The acdom was highly correlated with DOC and was found to have a conservative mixing behavior as the dominant process controlling its distribution, although differences among and within subregions were noted and related to differences in local river endmembers and seasonality. The acdom also dominated the absorption budget, even in long wavelengths of the visible range (e.g., 550 nm). Despite the highly light-absorptive characteristic of the waters, phytoplankton biomass was not negligeable, as shown by the chlorophyll-a (Chla) concentrations means that were almost always greater than 1 mg m−3. Analysis of the spectral shape of aphy and pigment ratios revealed a seasonal modulation in the composition of phytoplankton assemblages and photoacclimation. The optical properties of particulate matter showed a very dispersed relationship when compared to dry-mass concentration proxies in the study area, but the extremely low SPM-specific bbp values encountered were explained by the organic-rich characteristic of the nearshore zones of the EGSL. Short-term variability (atmospheric events) and the hydrodynamical regime also resulted in substantial variability in the optical properties of these areas. Overall, we provide a general parametrization for the relationships among the investigated inherent optical properties and dry-mass concentrations, which, in turn, will provide a baseline for tuning and developing regional remote sensing algorithms for the retrieval of biogeochemically relevant constituents of the water.

The Phase‐Locking of Tropical North Atlantic and the Contribution of ENSO

AbstractThe Tropical North Atlantic (TNA) is characterized by significant interannual variability in sea surface temperature (SST), which is phase‐locked to the boreal spring. In this study, the phase‐locking of TNA is investigated by adopting a linear stochastic‐dynamical model (SDM) using seasonally modulated TNA feedbacks together with the seasonal modulation of ENSO forcing. In the observations, the role of local TNA feedbacks and ENSO forcing in TNA phase‐locking are equivalently important with both preferring the peak of TNA variability to appear in the boreal spring. Besides, the seasonal modulation of TNA feedbacks and ENSO forcing strength are both mainly controlled by thermodynamic processes. In most climate models, the contribution of ENSO on TNA phase‐locking is weaker than that in observations. The strength of ENSO‐related TNA phase‐locking is highly correlated with the relationship between ENSO and TNA, which is mainly determined by the amplitude of ENSO and its teleconnection patterns.

Different mechanisms for the seasonal variations of the mesoscale eddy energy in the South China Sea

Using a recently developed functional analysis tool, Multiscale Window Transform (MWT) and the MWT-based theory of canonical transfer, this study investigates the dynamical processes responsible for the seasonal variability of the mesoscale eddies in the South China Sea (SCS). A three-scale energetics framework is employed, in which the original fields are decomposed into subfields on a nonstationary background flow window, a mesoscale eddy window and a high-frequency synoptic eddy window. Three local regions of high mesoscale eddy kinetic energy (EKE) levels, namely, the southwest of Taiwan Island (SWT), the southeast of Vietnam (SEV) and the northeast of the Natuna Island (NEN), are identified. The seasonal cycles of the mesoscale EKE in the three regions are not in phase, with peaks occurring around January, October and December, respectively. By diagnosing the canonical transfers between the background flow and the mesoscale eddies, we find that the seasonal cycle of the eddy variability in the SWT region is due to a mixed instability (baroclinic and barotropic instabilities), while barotropic instability plays a dominant role in determining the EKE seasonality in the SEV and NEN regions. This is quite different from the previous argument that baroclinic instability dominates the seasonal EKE in the SCS. The three-scale framework further reveals that high-frequency synoptic motions act to dissipate the lower-frequency mesoscale eddies through forward energy cascades. Besides the internal processes, external wind forcing is also found to influence the seasonal eddy variability, but is only limited to the NEN region. Our results highlight different mechanisms controlling the seasonal modulations of the mesoscale eddies in different regions of the SCS.

Seasonal Modulation of Dissolved Oxygen in the Equatorial Pacific by Tropical Instability Vortices

AbstractTropical instability vortices (TIVs) have a major influence on the physics and biogeochemistry of the equatorial Pacific. Using an eddy‐resolving configuration of the Community Earth System Model (CESM‐HR) and Lagrangian particle tracking, we examine TIV impacts on the three‐dimensional structure and variability of dissolved oxygen (O2) in the upper equatorial Pacific water column. In CESM‐HR, the simulated generation and westward propagation of TIVs from boreal summer through winter lead to the seasonal oxygenation of the upper northern equatorial Pacific, exhibited as a deepening of hypoxic depth west of 120°W. TIV effects on the equatorial Pacific oxygen balance are dominated by eddy‐advection and mixing, while indirect TIV effects on O2 consumption play minor roles. These advective effects reflect the transient displacements of isopycnals by eddy pumping as well as vortex transport of oxygen by eddy trapping, stirring, and subduction. TIVs influence on the upper equatorial Pacific O2 distribution and variability has important implications for understanding and modeling marine ecosystem dynamics and habitats, and should be taken into consideration in designing observation networks in this region.

Seasonal Modulation of Submesoscale Kinetic Energy in the Upper Ocean of the Northeastern South China Sea

AbstractAlthough submesoscale processes are revealed to have a strong seasonality in many regions of global ocean, their seasonal modulation in the northeastern South China Sea (NESCS) remains unexplored by observations. In this study, approaches to diagnose submesoscale kinetic energy (KE) and its conversion terms using data from a single mooring are proposed and validated. Based on these approaches, seasonal modulation of submesoscale KE in the NESCS is for the first time investigated using 8.7‐year‐long moored velocity and temperature data between August 2010 and April 2019. It is found that the monthly climatology of submesoscale KE shows an asymmetric annual cycle with a steep peak between December and February but a flat trough between April and October. The maximum and minimum of this annual cycle occur in January and May, respectively. Although the submesoscale KE rapidly decreases with depth, its seasonality is still evident at 300 m, which is far beneath the mixed layer. Statistical analysis suggests that the overall seasonality of submesoscale KE is shaped by mixed‐layer depth while its steep peak in winter is modulated by mesoscale strain rate. It therefore suggests that the combination of mixed‐layer instability and strain‐induced frontogenesis determines the detailed annual cycle of submesoscale KE. Energetics analysis demonstrates that submesoscales obtain their KE from the release of available potential energy but lose a small portion of its KE through inverse cascade. This submesoscale inverse KE cascade may play an important role in modulating the temporal variation of mesoscale KE in winter.

A Seasonal Harmonic Model for Internal Tide Amplitude Prediction

AbstractWe present an empirical model of the seasonal variability of the internal tide using seasonal harmonics to modulate the amplitude of the fundamental tidal constituents. Internal tide data, from both long‐term, in‐situ moorings and a mesoscale‐resolving and internal tide‐resolving ocean model, are used to demonstrate the performance of the seasonal harmonic model for the Indo‐Australian Basin region. The seasonal model describes up to 15% more of the observed (baroclinic) sea surface height variance than a fixed‐amplitude harmonic model at the mooring sites. The ocean model results demonstrate that the study region, which includes the Australian North West Shelf (NWS), Timor Sea, and southern Indonesian Islands, is dominated by standing wave interference patterns due to the presence of multiple generation sites. The seasonal harmonic model reveals that temporal shifts in the standing wave patterns coincide with seasonal variations in density stratification. This shift is particularly evident within distances of 2–3 internal wave lengths from strong generation sites. The fraction of the variance of the internal tide signal explained by seasonal modulations is largest in standing wave node regions, contributing to differences in predictive skill of the seasonal harmonic model at two moorings separated by only 38 km. Output of the harmonic model also demonstrates that the seasonally evolving internal tide propagating southward from Lombok Strait had a small amplitude in October when shear from the Indonesian Throughflow was strongest.

Variability and Sources of the Internal Wave Continuum Examined from Global Moored Velocity Records

AbstractEnergy for ocean turbulence is thought to be transferred from its presumed sources (viz., the mesoscale eddy field, near-inertial internal waves, and internal tides) to the internal wave continuum, and through the continuum via resonant triad interactions to breaking scales. To test these ideas, the level and variability of the oceanic internal gravity wave continuum spectrum are examined by computing time-dependent rotary spectra from a global database of 2260 current meter records deployed on 1362 separate moorings. Time series of energy in the continuum and the three “source bands” (near-inertial, tidal, and mesoscale) are computed, and their variability and covariability examined. Seasonal modulation of the continuum by factors of up to 5 is seen in the upper ocean, implicating wind-driven near-inertial waves as an important source. The time series of the continuum is found to correlate more strongly with the near-inertial peak than with the semidiurnal or mesoscale. The use of moored internal-wave kinetic energy frequency spectra as an alternate input to the traditional shear or strain wavenumber spectra in the Gregg–Henyey–Polzin finescale parameterization is explored and compared to traditional strain-based estimates.

Seasonal differences in hypothalamic thyroid-stimulating hormone β, gonadotropin-releasing hormone-I and deiodinase expression between migrant and resident subspecies of white-crowned sparrow (Zonotrichia leucophrys).

Across taxa, the seasonal transition between non-breeding and breeding states is controlled by localised thyroid hormone signalling in the deep brain via reciprocal switching of deiodinase enzyme expression from type 3 (DIO3) to type 2 (DIO2). This reciprocal switch is considered to be mediated by increasing thyroid-stimulating hormone β (TSHβ) release from the pars tuberalis, which occurs in response to a change in photoperiod. Although well characterised in a handful of model organisms in controlled laboratory settings, this pathway remains largely unexplored in free-living animals under natural environmental conditions. In this comparative gene expression study, we investigated hypothalamic thyroid hormone signalling in two seasonally breeding subspecies of white-crowned sparrow (Zonotrichia leucophrys), across the entirety of their annual cycles. The migratory Gambel's (Z. l. gambelii) and resident Nuttall's (Z. l. nuttalii) subspecies differ with respect to timing of reproduction, as well as life history stage and migratory strategies. Although DIO3mRNA expression was elevated and DIO2mRNA expression was reduced in the wintering period in both subspecies, DIO2 peaked in both subspecies prior to the onset of reproduction. However, there was differential timing between subspecies in peak DIO2 expression. Intriguingly, seasonal modulation of TSHβ mRNA was only observed in migrants, where expression was elevated at the start of breeding, consistent with observations from other highly photoperiodic species. There was no correlation between TSHβ, DIO2 and gonadotropin-releasing hormone-I mRNA or reproductive metrics in residents. Based on these observed differences, we discuss potential implications for our understanding of how changes in medial basal hypothalamic gene expression mediates initiation of seasonal reproduction.

Seasonal modulation of antibody response to diphtheria-tetanus-pertussis vaccination in infants: a cohort study in rural Gambia

BackgroundIn rural Gambia, rates of malnutrition and infection are higher during the annual rainy/‘hungry’ season (June–October) in comparison to the dry/‘harvest’ season (November–May). The effects of this seasonal pattern on an infant’s immune development and their capacity to respond to childhood vaccinations remain unclear. The aim of the current analysis was to determine whether antibody responses to diphtheria-tetanus-pertussis (DTP) vaccinations in infants differ between seasons.MethodsInfants received the DTP vaccine at 8, 12 and 16 weeks of age and antibody titres were measured in blood samples collected at 12 (n = 710) and 24 (n = 662) weeks of age. Mean DTP antibody titres, adjusted for maternal and infant confounders, were compared by t-tests and the effect sizes of the mean differences were calculated between seasons at mid-gestation (20 weeks gestation) and first vaccination (8 weeks of infant age).ResultsA smaller number of infants received their first vaccination during the rainy/hungry season months compared to the dry/harvest season (n = 224 vs. n = 486). At 12 weeks, infants vaccinated during the rainy/hungry season had lower weight-for-length Z-scores (p = 0.01) and were more likely to be anaemic (p < 0.001). Their mothers, however, were pregnant mostly during the dry/harvest season, had higher weight gain (p < 0.001) and were less likely to be anaemic during pregnancy (p < 0.001). At 12 weeks, infants vaccinated during the rainy/hungry season had significantly higher mean diphtheria, tetanus and pertussis antibody titres; by 62.3, 16.9 and 19.7%, respectively (all, p < 0.001). However, at 24 weeks, they had lower mean anti-diphtheria titres (by 20.6%, p < 0.001) compared with infants vaccinated during the dry/harvest season, and no differences were observed in mean tetanus and pertussis antibody titres by vaccination season.ConclusionsInfant antibody response to the primary dose of the DTP vaccine was influenced by both season of pregnancy and infancy, although effects were diminished following three doses. Environmental exposures, including nutrition, to both the mother and infant are hypothesised as likely drivers of these seasonal effects.

Surges of Harald Moltke Bræ, north-western Greenland: seasonal modulation and initiation at the terminus

Abstract. Harald Moltke Bræ, a marine-terminating glacier in north-western Greenland, shows episodic surges. A recent surge from 2013 to 2019 lasted significantly longer (6 years) than previously observed surges (2–4 years) and exhibits a pronounced seasonality with flow velocities varying by 1 order of magnitude (between about 0.5 and 10 m d−1) in the course of a year. During this 6-year period, the seasonal velocity always peaked in the early melt season and decreased abruptly when meltwater runoff was maximum. Our data suggest that the seasonality has been similar during previous surges. Furthermore, the analysis of satellite images and digital elevation models shows that the surge from 2013 to 2019 was preceded by a rapid frontal retreat and a pronounced thinning at the glacier front (30 m within 3 years). We discuss possible causal mechanisms of the seasonally modulated surge behaviour by examining various system-inherent factors (e.g. glacier geometry) and external factors (e.g. surface mass balance). The seasonality may be caused by a transition of an inefficient subglacial system to an efficient one, as known for many glaciers in Greenland. The patterns of flow velocity and ice thickness variations indicate that the surges are initiated at the terminus and develop through an up-glacier propagation of ice flow acceleration. Possibly, this is facilitated by a simultaneous up-glacier spreading of surface crevasses and weakening of subglacial till. Once a large part of the ablation zone has accelerated, conditions may favour substantial seasonal flow acceleration through seasonally changing meltwater availability. Thus, the seasonal amplitude remains high for 2 or more years until the fast ice flow has flattened the ice surface and the glacier stabilizes again.

Seasonal changes in sediment erodibility in a sandy carbonate environment detected from turbidity time series

Sediment resuspension and sediment erodibility were investigated in Hamelin Pool (Western Australia), which is one of the few modern carbonate settings where stromatolites and ooids are actively forming. For this purpose, the first time series of wave height and water turbidity were recorded at a ~2.5 m deep subtidal location in Hamelin Pool from July 2017 to March 2018. Sediment grain size analyses indicate that this environment is nearly free of mud, so the optical turbidity sensor was able to detect the intra-wave modulation of sand resuspension. This allowed us to use the standard deviation of the turbidity within a burst – as opposed to the mean turbidity – as a proxy for sand resuspension. This approach was further validated by wave tank experiments, which also helped to identify the occurrence of biofouling and discard the affected data. Although the wave regime was similar throughout the year, sand resuspension changed with seasons. Sediment erodibility, defined as the sand resuspension normalized by the bed shear stress, was higher during the Austral winter and spring, and lower in summer and autumn. This decrease in erodibility coincided with an increase in temperature and solar irradiance. These two environmental factors likely modulate the growth of benthic microbes, which in turn affects sediment dynamics. This seasonal modulation of sediment dynamics may influence additional processes, including the delivery of sand grains to stromatolites and the precipitation of aragonite around ooids and in stromatolite laminae.

The problematicΨ1 ocean tide

SUMMARYObservations of the ψ1 earth tide yield valuable insights into the earth’s free core nutation, especially if the effects of the ψ1 ocean tide can be removed. The ocean tide is extremely small, with amplitudes rarely more than a few millimetres, and developing an accurate model is challenging. Direct observations are inadequate to support a global model. The alternative—numerical simulation—must account for a multitude of possible effects. The ocean tide is forced by the gravitational tidal potential, by pressure loading from atmospheric tides, by seasonal modulation of the nearby K1 constituent, and possibly by non-linear interactions among several other constituents. Here we construct a model of the ψ1 ocean tide which accounts for (or attempts to bound) each of these effects. The radiational component (from atmospheric pressure loading), although relatively small, is complicated by the presence of non-tidal atmospheric variability in the diurnal band. The ocean’s response is dynamic, but there is also high-wavenumber pressure forcing with a near-isostatic response. A general circulation model, forced by both winds and the tidal potential, suggests that annual variability in K1 leads to pronounced ψ1 amplitudes in some marginal seas, especially in the western Pacific.

Ecophysiological and morpho-functional responses of mediterranean plants on coastal dunes: How they vary across seasons

Coastal dunes of the Mediterranean basin are threatened ecosystems, conservation of which is vital for both ecological and economic reasons. Understanding how dune plants and their habitat interact may deepen our knowledge of the dynamics of coastal environments. An ecophysiological and morpho-functional investigation was carried out throughout all seasons on four species typically found on the fixed dunes of central Italy. They belong to different functional groups: Cistus creticus subsp. Eriocephalus (drought semideciduous), Phillyrea angustifolia (evergreen sclerophyll), Juniperus macrocarpa (conifer) and Spartium junceum (leguminous). The aims of the study were to determine the annual patterns of plant responses, to highlight putative differences of resistance strategies between functional groups, and to identify traits which play a crucial role in plant adaptation to dune environments. Photochemical efficiency was lower in winter for all species, although it was quite steady in Juniperus. Water status never reached critical levels, probably because the summer under analysis was wetter than average. Different strategies of resistance were exhibited: leaf morphological traits and seasonal modulation of leaf pigments changed depending on the functional group. Nevertheless, all species displayed efficient adaptation to the Mediterranean environment involved in the study, showing the critical importance of how physiological and functional adjustments combine in different ways. In particular, leaf area, total carotenoid and total chlorophyll concentrations performed a prominent role in explaining how the studied plants adapt to the fixed dune environment.

Static and Dynamic Analysis of Seasonal Tilt Solar Module Mounting Structure

This paper highlights the concept of a ground-mounted solar PV plant. It deals with the ground-mounted solar photovoltaic design, and development using numerical analysis under static and dynamic conditions. Ground-mounted solar components are made up of steel shows superior performance and is cost-effective. CFD analysis is executed on the structure of the study for flow and assessment of wind pressure on the developed model using Indian environmental conditions. The CFD results have been compared and validated h the analytical calculations obtained through IS 875 codes part 3 for wind pressure. Structural FE analysis is carried out to ensure structural stability for the given hazardous environmental conditions like wind load. Also, modal analysis is carried out to study the effect of dynamic loading.

The oscillation-outbreaks characteristic of the COVID-19 pandemic.

The evolution of the COVID-19 pandemic features the alternation of oscillations and abrupt rises. The oscillations are attributable to weekly and seasonal modulations, while abrupt rises are stimulated by mass gatherings.