Start Of Season Research Articles

Physiographic Controls on Landfast Ice Variability from 20 Years of Maximum Extents across the Northwest Canadian Arctic

Landfast ice is a defining feature among Arctic coasts, providing a critical transport route for communities and exerting control over the exposure of Arctic coasts to marine erosion processes. Despite its significance, there remains a paucity of data on the spatial variability of landfast ice and limited understanding of the environmental processes’ controls since the beginning of the 21st century. We present a new high spatiotemporal record (2000–2019) across the Northwest Canadian Arctic, using MODIS Terra satellite imagery to determine maximum landfast ice extent (MLIE) at the start of each melt season. Average MLIE across the Northwest Canadian Arctic declined by 73% in a direct comparison between the first and last year of the study period, but this was highly variable across regional to community scales, ranging from 14% around North Banks Island to 81% in the Amundsen Gulf. The variability was largely a reflection of 5–8-year cycles between landfast ice rich and poor periods with no discernible trend in MLIE. Interannual variability over the 20-year record of MLIE extent was more constrained across open, relatively uniform, and shallower sloping coastlines such as West Banks Island, in contrast with a more varied pattern across the numerous bays, headlands, and straits enclosed within the deep Amundsen Gulf. Static physiographic controls (namely, topography and bathymetry) were found to influence MLIE change across regional sites, but no association was found with dynamic environmental controls (storm duration, mean air temperature, and freezing and thawing degree day occurrence). For example, despite an exponential increase in storm duration from 2014 to 2019 (from 30 h to 140 h or a 350% increase) across the Mackenzie Delta, MLIE extents remained relatively consistent. Mean air temperatures and freezing and thawing degree day occurrences (over 1, 3, and 12-month periods) also reflected progressive northwards warming influences over the last two decades, but none showed a statistically significant relationship with MLIE interannual variability. These results indicate inferences of landfast ice variations commonly taken from wider sea ice trends may misrepresent more complex and variable sensitivity to process controls. The influences of different physiographic coastal settings need to be considered at process level scales to adequately account for community impacts and decision making or coastal erosion exposure.

The duration and severity of the allergenic pollen season in Istanbul, and the role of meteorological factors

Information on the allergenic pollen season provides insight on the state of the environment of a region and facilitates allergy symptom management. We present a retrospective analysis of the duration and severity of the allergenic pollen season and the role of meteorological factors in Istanbul, Turkey. Aerobiological sampling from January 2013 to June 2016, pollen identification and counting followed current standard methodology. Pollen seasons were defined according to 95% of the Annual Pollen Integral (APIn) and the season start date was compared with the first day of 5 day consecutive non-zero records. Generalized additive models (GAMs) were created to study the effect of meteorological factors on flowering. The main pollen contributors were taxa of temperate and Mediterranean climates, and neophytic Ambrosia. Cupressaceae, Poaceae, Pinaceae, Quercus and Ambrosia had the greatest relative abundance. The pollen season defined on 95% of the APIn was adequate for our location with total APIns around 10.000 pollen*day*m−3. Woody taxa had generally shorter seasons than herbaceous taxa. In trees, we see precipitation as the main limiting factor for assimilate production prior to anthesis. A severe tree pollen season in 2016 suggests intense synchronous flowering across taxa and populations triggered by favourable water supply in the preceding year. GAM models can explain the effect of weather on pollen concentrations during anthesis. Under the climatic conditions over the study period, temperature had a negative effect on spring flowering trees, and a positive one on summer flowering weeds. Humidity, atmospheric pressure and precipitation had a negative effect on weeds. Our findings contribute to environmental and allergological knowledge in southern Europe and Turkey with relevancy in the assessment of impacts of climate change and the management of allergic disease.

Earlier green-up and senescence of temperate United States rangelands under future climate

Climate and vegetation phenology are closely linked, and climate change is already impacting phenology in many systems. These impacts are expected to progress in the future. We sought to forecast future shifts in rangeland growing season timing due to climate change, and interpret their importance for land management and ecosystem function. We trained a model on remotely sensed land surface phenology and climate data collected from 2001 to 2014 in temperate United States rangelands. We used this model to forecast annual growing season start dates, end dates, and season length through 2099 among six general circulation models and under RCP 4.5 and 8.5 scenarios. Growing season start was projected to shift earlier throughout our study area. In 2090–2099, start of season advanced by an average of 10 (RCP 4.5) to 17 (RCP 8.5) days. End of season also advanced by 12 (RCP 4.5) to 24 (RCP 8.5) days, but with greater heterogeneity. Start and end of season change mainly offset one another, so growing season length changes were lesser (2 days in RCP 4.5, and 7 in RCP 8.5). Some mountainous areas experienced both earlier start of season and later end of season, lengthening their growing season. Earlier phenology in rangelands would force adaptation in grazing and impact ecosystem function. Mountainous areas with earlier start and later end of season may become more viable for grazing, but most areas may experience slightly shortened growing seasons. Autumn phenology warrants greater research, and our finding of earlier autumn senescence contradicts some prior research.

Energy-efficient microclimate formation in a historical religious monument building with wall paintings

In order to preserve complex historical objects with unique architectural, engineering solutions and monumental art that are of cultural and historical value, the task of maintaining the microclimate parameters determined by museum specialists is relevant. The object of the study is St. Sophia Cathedral – a monument of architecture, history and monumental painting of national importance, which is a UNESCO World Cultural Heritage Site. The location of it in the city centre determines the influence of adverse outdoor conditions, in particular, high air pollution, and the attraction of the site – a high level of attendance and, as a result, dynamic changes in the indoor parameters of the air environment. The existing regime of heat, moisture and gases in the St. Sophia Cathedral is periodic with characteristic maxima of temperature and relative humidity values in different areas of the building when people visit it. Three series of natural studies of the air environment parameters in the Cathedral were carried out. The first series was held on 02 October 2019 at an outdoor temperature of plus 18.9 °C and a relative humidity of 47.5 % with the ventilation system turned off and on before the start of the heating season. The second series of measurements was carried out on 12-14 November 2019 at an outside air temperature of plus 8.9 °C and a relative humidity of 73 % with the ventilation turned off and the heating turned on. The third series of measurements was carried out on 08 February 2020 at an outside air temperature of minus 3.2 °C and a relative humidity of 56.2 % with ventilation off and heating on. An analysis of the results indicates the need for reconstruction and modernization of the engineering microclimate systems and heat supply of the Cathedral. Currently, the physical deterioration of heating and ventilation systems is 75-85%. They need immediate reconstruction and change of operating mode. Taking into account the performed field studies, a project for the modernization of heating, ventilation and air conditioning systems was developed.

Multi-Season Phenology Mapping of Nile Delta Croplands Using Time Series of Sentinel-2 and Landsat 8 Green LAI.

Space-based cropland phenology monitoring substantially assists agricultural managing practices and plays an important role in crop yield predictions. Multitemporal satellite observations allow analyzing vegetation seasonal dynamics over large areas by using vegetation indices or by deriving biophysical variables. The Nile Delta represents about half of all agricultural lands of Egypt. In this region, intensifying farming systems are predominant and multi-cropping rotations schemes are increasing, requiring a high temporal and spatial resolution monitoring for capturing successive crop growth cycles. This study presents a workflow for cropland phenology characterization and mapping based on time series of green Leaf Area Index (LAI) generated from NASA’s Harmonized Landsat 8 (L8) and Sentinel-2 (S2) surface reflectance dataset from 2016 to 2019. LAI time series were processed for each satellite dataset, which were used separately and combined to identify seasonal dynamics for a selection of crop types (wheat, clover, maize and rice). For the combination of L8 with S2 LAI products, we proposed two time series smoothing and fitting methods: (1) the Savitzky–Golay (SG) filter and (2) the Gaussian Processes Regression (GPR) fitting function. Single-sensor and L8-S2 combined LAI time series were used for the calculation of key crop Land Surface Phenology (LSP) metrics (start of season, end of season, length of season), whereby the detection of cropland growing seasons was based on two established threshold methods, i.e., a seasonal or a relative amplitude value. Overall, the developed phenology extraction scheme enabled identifying up to two successive crop cycles within a year, with a superior performance observed for the seasonal than for the relative threshold method, in terms of consistency and cropland season detection capability. Differences between the time series collections were analyzed by comparing the phenology metrics per crop type and year. Results suggest that L8-S2 combined LAI data streams with GPR led to a more precise detection of the start and end of growing seasons for most crop types, reaching an overall detection of 74% over the total planted crops versus 69% with S2 and 63% with L8 alone. Finally, the phenology mapping allowed us to evaluate the spatial and temporal evolution of the croplands over the agroecosystem in the Nile Delta.

A Cohort Study on the Duration of Plasmodium falciparum Infections During the Dry Season in The Gambia.

BackgroundIn areas where Plasmodium falciparum malaria is seasonal, a dry season reservoir of blood-stage infection is essential for initiating transmission during the following wet season.MethodsIn The Gambia, a cohort of 42 individuals with quantitative polymerase chain reaction-positive P falciparum infections at the end of the transmission season (December) were followed monthly until the end of the dry season (May) to evaluate infection persistence. The influence of human host and parasitological factors was investigated.ResultsA large proportion of individuals infected at the end of the wet season had detectable infections until the end of the dry season (40.0%; 16 of 40). At the start of the dry season, the majority of these persistent infections (82%) had parasite densities >10 p/µL compared to only 5.9% of short-lived infections. Persistent infections (59%) were also more likely to be multiclonal than short-lived infections (5.9%) and were associated with individuals having higher levels of P falciparum-specific antibodies (P = .02).ConclusionsAsymptomatic persistent infections were multiclonal with higher parasite densities at the beginning of the dry season. Screening and treating asymptomatic infections during the dry season may reduce the human reservoir of malaria responsible for initiating transmission in the wet season.

Insights into the Usefulness of a New Extreme Weather Guidance Tool: The Long-Range Tropical Cyclone Outlook for the Southwest Pacific (TCO-SP)

Abstract Tropical cyclones (TCs) produce extreme winds, large waves, storm surges, intense rainfall, and flooding and account for almost 75% of natural disasters across the southwest Pacific (SWP) region. The island nations and territories across the SWP rely on seasonal TC outlooks for insights into possible risks for the coming TC season. Launched in July 2020, the Long-Range Tropical Cyclone Outlook for the Southwest Pacific (TCO-SP) provides deterministic (frequency) and probabilistic (likelihood) TC outlooks for 12 subregional and island-scale locations up to 4 months (July) before the start of the SWP TC season (November–April). Following TCO-SP’s first season of operation, this study (i) outlines the process of generating and communicating TCO-SP outlooks, (ii) provides a postseason validation of TCO-SP performance on the 2020/21 SWP TC season, and (iii) reports on the results of a questionnaire used to determine end-user needs and user-perceived usefulness of TCO-SP. Postseason validation indicates that TCO-SP successfully predicted a near-normal SWP TC season. Island- and regional-scale guidance also performed well, with an average skill score of 54% across all regions. Analysis of responses to a TCO-SP questionnaire revealed a diverse and global user base that indicate the core features of TCO-SP (island-scale/regional-scale outlooks, regular monthly updates, and an outlook lead time up to 4 months before the start of the TC season) are particularly useful. TCO-SP will continue to innovate to deliver reliable and trusted TC outlooks with a goal to reduce disaster risk and increase resilience across the SWP region.

Male ant reproductive investment in a seasonal wet tropical forest: Consequences of future climate change.

Tropical forests sustain many ant species whose mating events often involve conspicuous flying swarms of winged gynes and males. The success of these reproductive flights depends on environmental variables and determines the maintenance of local ant diversity. However, we lack a strong understanding of the role of environmental variables in shaping the phenology of these flights. Using a combination of community-level analyses and a time-series model on male abundance, we studied male ant phenology in a seasonally wet lowland rainforest in the Panama Canal. The male flights of 161 ant species, sampled with 10 Malaise traps during 58 consecutive weeks (from August 2014 to September 2015), varied widely in number (mean = 9.8 weeks, median = 4, range = 1 to 58). Those species abundant enough for analysis (n = 97) flew mainly towards the end of the dry season and at the start of the rainy season. While litterfall, rain, temperature, and air humidity explained community composition, the time-series model estimators elucidated more complex patterns of reproductive investment across the entire year. For example, male abundance increased in weeks when maximum daily temperature increased and in wet weeks during the dry season. On the contrary, male abundance decreased in periods when rain receded (e.g., at the start of the dry season), in periods when rain fell daily (e.g., right after the beginning of the wet season), or when there was an increase in the short-term rate of litterfall (e.g., at the end of the dry season). Together, these results suggest that the BCI ant community is adapted to the dry/wet transition as the best timing of reproductive investment. We hypothesize that current climate change scenarios for tropical regions with higher average temperature, but lower rainfall, may generate phenological mismatches between reproductive flights and the adequate conditions needed for a successful start of the colony.

Participatory validation and optimization of the Triple S method for sweetpotato planting material conservation in southern Ethiopia

Abstract A climate-resilient, root-based sweetpotato planting material (SPM) conservation method called “Triple S” or “Storage in Sand and Sprouting” has created timely access to sweetpotato planting material in areas with a prolonged dry season in Uganda and Tanzania. The aim of this study was to validate and optimize the Triple S method for conservation of sweetpotato planting material in dry areas of southern Ethiopia. The Triple S method was validated in four districts of southern Ethiopia on varieties Kulfo and Awassa 83 and compared with two common local planting material conservation methods: leaving “volunteer roots” in the soil which then sprout at the onset of rains; and planting vines under shade or mulch. Across study locations and for both varieties, Triple S resulted in a higher survival rate (81–95%) in storage during the dry season compared to the local conservation methods (7–57%). Plants of both varieties grown from roots conserved with the Triple S method showed significantly higher vine growth and lower weevil and virus infection symptoms compared to plants grown from the two local conservation methods. An additional experiment found that planting at the start of the main rainy season in June and harvesting just before the start of the dry season in October gives the highest number of medium-sized and weevil-free roots suitable for Triple S. The current study demonstrated that the Triple S method is a promising technology for small-scale sweetpotato farmers in dry areas for timely access to high-quality planting material

Objective Criteria to Determine the Rainy Season Onset Date for the Central Highlands and Southern Vietnam

In this study, a new approach to selecting the Rainy Season Onset Date (hereafter denoted as RSOD) criteria is proposed and applied for Central Highlands and Southern Vietnam based on daily rainfall station data from 1979 to 2015. This approach bases on the similarity between station-based RSODs and regional-scale RSOD signal, obtained by applying Multi variable Principal Component Analysis (MPCA). The results show that these selected criteria can capture reasonably the heterogeneity of the start of the rainy season on both regional- and local-scale. The determined RSODs for the Central Highlands and the South are consistent with previous studies. It suggests the application potential of this approach in objectively determining the suitable RSOD criteria for each station (local-scale) in other regions.

Real-Time Detection of Flu Season Onset: A Novel Approach to Flu Surveillance.

The current gold standard for detection of flu season onset in the USA is done retrospectively, where flu season is detected after it has already started. We aimed to create a new surveillance strategy capable of detecting flu season onset prior to its starting. We used an established data generation method that combines Google search volume and historical flu activity data to simulate real-time estimates of flu activity. We then applied a method known as change-point detection to the generated data to determine the point in time that identifies the initial uptick in flu activity which indicates the imminent onset of flu season. Our strategy exhibits a high level of accuracy in predicting the onset of flu season at 86%. Additionally, on average, we detected the onset three weeks prior to the official start of flu season. The results provide evidence to support both the feasibility and efficacy of our strategy to improve the current standard of flu surveillance. The improvement may provide valuable support and lead time for public health officials to take appropriate actions to prevent and control the spread of the flu.

How to select the optimal monitoring locations for an aerobiological network: A case of study in central northwest of Spain

Airborne pollen concentration varies depending on several factors, such as local plant biodiversity, geography and climatology. These particles are involved in triggering pollinosis in a share of worldwide human population, and adequate monitoring is, therefore, important. However, the pollen traps in aerobiological monitoring networks are usually installed in cities, and the features of the whole territory are not taken into account. The aim of this study was to analyze what environmental parameters are more suitable as regards setting up monitoring stations throughout a territory in order to obtain an aerobiological network that can represent environmental diversity. The analysis was carried out in 13 locations in Castilla y León over an 8 year period. This is a favorable territory in which to conduct this type of study owing to its climatic features, orography and biodiversity. The ten most abundant pollen types in the region were analyzed, and a clustering analysis was calculated with different distances so as to obtain homogeneous groups of stations. Moreover, the clusters obtained were analyzed in combination with altitudinal and different bioclimatic parameters, which derived from temperature and precipitation.The result here shows that the Castilla y León aerobiological network RACYL represents most of the environmental variability of the territory. Furthermore, it can be divided into two clusters and five sub-clusters for which the start of the main pollen season is different. This corresponds with the division of the territory as regards bioclimatic conditions. The most important bioclimatic parameters were the seasonality of the precipitation and the maximum temperature of the warmest month, although orography must also be taken into account. All of these help discover the optimal places in which to install traps and could reduce the number of monitoring stations. This study additionally provides data for unmonitored areas with similar bioclimatic conditions to those monitored.

Nirsevimab for Prevention of RSV in Healthy Late-Preterm and Term Infants

BackgroundRespiratory syncytial virus (RSV) is a major cause of lower respiratory tract infection and hospitalization in infants. Nirsevimab is a monoclonal antibody to the RSV fusion protein that has an extended half-life. The efficacy and safety of nirsevimab in healthy late-preterm and term infants are uncertain.MethodsWe randomly assigned, in a 2:1 ratio, infants who had been born at a gestational age of at least 35 weeks to receive a single intramuscular injection of nirsevimab or placebo before the start of an RSV season. The primary efficacy end point was medically attended RSV-associated lower respiratory tract infection through 150 days after the injection. The secondary efficacy end point was hospitalization for RSV-associated lower respiratory tract infection through 150 days after the injection.ResultsA total of 1490 infants underwent randomization: 994 were assigned to the nirsevimab group and 496 to the placebo group. Medically attended RSV-associated lower respiratory tract infection occurred in 12 infants (1.2%) in the nirsevimab group and in 25 infants (5.0%) in the placebo group; these findings correspond to an efficacy of 74.5% (95% confidence interval [CI], 49.6 to 87.1; P<0.001) for nirsevimab. Hospitalization for RSV-associated lower respiratory tract infection occurred in 6 infants (0.6%) in the nirsevimab group and in 8 infants (1.6%) in the placebo group (efficacy, 62.1%; 95% CI, −8.6 to 86.8; P=0.07). Among infants with data available to day 361, antidrug antibodies after baseline were detected in 58 of 951 (6.1%) in the nirsevimab group and in 5 of 473 (1.1%) in the placebo group. Serious adverse events were reported in 67 of 987 infants (6.8%) who received nirsevimab and in 36 of 491 infants (7.3%) who received placebo.ConclusionsA single injection of nirsevimab administered before the RSV season protected healthy late-preterm and term infants from medically attended RSV-associated lower respiratory tract infection. (Funded by MedImmune/AstraZeneca and Sanofi; MELODY ClinicalTrials.gov number, NCT03979313.)

Sex-specific aging in bite force in a wild vertebrate.

The manifold differences between the sexes provide wide scope for sex differences in senescence. However, detecting physiological decline in old age and evaluating any sex difference in aging in a wild population can be challenging. This applies especially to long-lived species that require marking around birth in order to recognize elderly individuals, perhaps decades later. Here, we used bite force of known-age, long-lived Nazca boobies (Sula granti, a seabird) as a functional measure of muscle strength; surprisingly, only a single study has evaluated the possibility of senescent decline in muscle strength in a wild vertebrate. The male-biased adult sex ratio of this population constrains breeding opportunities across the lifespan for males, so we predicted that slower accumulation of reproductive costs would delay senescent decline in bite force in males compared to females, matching observed patterns in some non-muscle traits in this species. Data were collected from 349 adults using a force transducer at the start of the breeding season in November 2017 on Isla Española, Galápagos. Both sexes achieved less bite force in late life. The decline began at a later age in males, providing evidence of sex-specific schedules of decline in muscle function in a wild vertebrate.

Relationships between prostaglandin concentrations, a single nucleotide polymorphism in HSD17B12, and reproductive performance in dairy cows

Prostaglandins are involved in multiple processes important for fertility, with previous work in mice highlighting a potential role for the HSD17B12 gene in prostaglandin biosynthesis. This study aimed to determine the associations among circulating prostaglandin concentrations, a missense SNP in the HSD17B12 gene predicted to disrupt protein function, and fertility traits in first-lactation Holstein-Friesian dairy cows. We used a study population of approximately 500 animals specifically bred to have either a positive (POS, +5%) or negative (NEG, -5%) genetic merit for fertility (FertBV). Genotypes of a previously identified SNP (rs109711583) in HSD17B12 were determined, with 116 animals genotyped as AA, 215 genotyped as AG, and 153 genotyped as GG. Plasma concentrations of prostaglandin E2 and the PGF2α metabolite PGFM were determined at 3 time points (12 mo of age, 4 d postpartum, and 5 wk postpartum during first lactation) in a selection of animals with AA and GG genotypes from both the POS and NEG FertBV groups (n = 33-40 in each genotype for each FertBV group). Binary reproductive traits (yes or no) examined included submission for artificial breeding in the first 3 or 6 wk of the seasonal breeding period; conception to first service; conception during the first 6 wk of the breeding period; and pregnant at the end of the breeding period. Uterine health at 6 wk after calving was examined by evaluating the percentage of polymorphonuclear leukocytes following uterine cytology and by scoring vaginal discharge based on the presence of purulent material. The 3-wk submission rate was increased in animals that carried the G allele of the missense SNP in HSD17B12, but no differences were present among genotypes for 6-wk submission rate. The trait was additive, with each increase of the G allele increasing the 3-wk submission rate by 6 to 7%. We did not observe any consistent associations between SNP alleles and circulating PGE2 concentrations; however, a complex 3-way interaction among time, fertility group, and SNP allele was present for PGFM concentrations. Plasma concentrations of PGE2 were increased approximately 40% at 5 wk postpartum in animals that were submitted for breeding within 3 or 6 wk of the start of the breeding season, and in those that conceived during the first 6 wk of breeding, compared with those that did not. Plasma concentrations of PGFM were decreased approximately 20% in those animals that conceived to their first service and tended to be decreased in animals that were pregnant at the end of the breeding period, compared with those that were not. In summary, associations were observed between the SNP in HSD17B12 and submission rate by d 21 of the breeding season, as well as between circulating prostaglandin concentrations and fertility traits, but the SNP was not consistently linked to changes in prostaglandin concentrations. Thus, the association between submission rate by d 21 of the breeding season and the SNP in HSD17B12 were unlikely driven by changes in prostaglandins.

Trends in malaria epidemiological factors following the implementation of current control strategies in Dangassa, Mali

BackgroundOver the past decade, three strategies have reduced severe malaria cases and deaths in endemic regions of Africa, Asia and the Americas, specifically: (1) artemisinin-based combination therapy (ACT); (2) insecticide-treated bed nets (ITNs); and, (3) intermittent preventive treatment with sulfadoxine-pyrimethamine in pregnancy (IPTp). The rationale for this study was to examine communities in Dangassa, Mali where, in 2015, two additional control strategies were implemented: ITN universal coverage and seasonal malaria chemoprevention (SMC) among children under 5 years old.MethodsThis was a prospective study based on a rolling longitudinal cohort of 1401 subjects participating in bi-annual smear surveys for the prevalence of asymptomatic Plasmodium falciparum infection and continuous surveillance for the incidence of human disease (uncomplicated malaria), performed in the years from 2012 to 2020. Entomological collections were performed to examine the intensity of transmission based on pyrethroid spray catches, human landing catches and enzyme-linked immunosorbent assay (ELISA) testing for circumsporozoite antigen.ResultsA total of 1401 participants of all ages were enrolled in the study in 2012 after random sampling of households from the community census list. Prevalence of infection was extremely high in Dangassa, varying from 9.5 to 62.8% at the start of the rainy season and from 15.1 to 66.7% at the end of the rainy season. Likewise, the number of vectors per house, biting rates, sporozoites rates, and entomological inoculation rates (EIRs) were substantially greater in Dangassa.DiscussionThe findings for this study are consistent with the progressive implementation of effective malaria control strategies in Dangassa. At baseline (2012–2014), prevalence of P. falciparum was above 60% followed by a significant year-to-year decease starting in 2015. Incidence of uncomplicated infection was greater among children < 5 years old, while asymptomatic infection was more frequent among the 5–14 years old. A significant decrease in EIR was also observed from 2015 to 2020. Likewise, vector density, sporozoite rates, and EIRs decreased substantially during the study period.ConclusionEfficient implementation of two main malaria prevention strategies in Dangassa substantially contribute to a reduction of both asymptomatic and symptomatic malaria from 2015 to 2020.

Isokinetic muscle strength cannot be related to the odds ratio of musculoskeletal injuries in young elite wrestlers

BackgroundWrestling is considered one of the oldest sports in the world. There is a high rate of injuries in Wrestling. To prevent injuries, it is necessary to identify the risk factors. Despite the functional importance of strength in wrestling, few studies have investigated the relationship between isokinetic strength and the rate of injuries in the sport.ObjectivesThe objective of the present study was to investigate the relationship between the isokinetic strength of elite wrestlers and the rate of injuries prospectively.MethodA total of 72 young wrestlers with at least 2 years of experience in the Tehran Wrestling Premier League participated in this study. Before the start of the competition season, the isokinetic strength of flexor and extensor muscles of the knee and shoulder were measured at different velocities by an isokinetic dynamometer. The injuries and training hours of these wrestlers were then recorded for nine months.ResultsThe study results showed no significant relationship between isokinetic strength of flexor and extensor muscles of the knee or shoulder at different angular speeds of 60, 180, and 300°/s. There was neither significant between the ratio of the strength flexor/extensor for knee and/or shoulder in young elite wrestlers with injuries.ConclusionIsokinetic strength of lower and upper limb muscles alone cannot predict wrestlers' injuries. Therefore, the use of these tests is not recommended to evaluate the risk of injury in this population.

Comparison of Phenology Estimated From Monthly Vegetation Indices and Solar-Induced Chlorophyll Fluorescence in China

Phenology is an important biological indicator for monitoring terrestrial ecosystems and global change. Solar-induced chlorophyll fluorescence (SIF) emitted by chlorophyll has been proven to characterize vegetation photosynthesis and phenology. In this study, we used monthly normalized difference vegetation index (NDVI), enhanced vegetation index (EVI), and SIF products to qualitatively compare the effectiveness at detecting the phenological characteristics (SOS (start-of-season), EOS (end-of-season), and LOS (length-of-season)) over China during 2007–2013. The phenological characteristics determined by gross primary productivity (GPP) were applied as the reference to validate the phenological characteristics derived from NDVI, EVI, and SIF. The results demonstrated that the phenological characteristics derived from SIF were more consistent with that of GPP than VIs (NDVI and EVI) when considering all latitude grades, different elevation grades, and different land cover types in China. In the middle- and high-latitude regions, SOS derived from the vegetation indices (SOSVIs) did not deviate from those from GPP (SOSGPP) and SIF (SOSSIF), while in low latitudes, SOSVIs were about 20 d later than SOSSIF and SOSGPP. The VIs (EOSVIs) had a severe lag behind those of SIF (EOSSIF) in estimating the EOS at all latitudes. The EOSSIF had a deviation of fewer than 5 d compared with EOS estimated by GPP (EOSGPP), whereas the deviation of EOSVIs from EOSGPP was about 10–31 d across low to high latitude regions. The biases of SIF and VIs were due to the inconsistency between vegetation photosynthesis and leaf greenness. Also, VIs overestimated the LOS at all latitudes, the difference of LOS between estimated by NDVI and estimated by GPP was as long as 39 d in the high-latitude region. Our study suggests that SIF is suitable for estimating the phenological characteristics of vegetation regardless of different latitudes, elevation grades, and land cover types in China, providing a basis for SIF to study the vegetation phenological characteristics in a regional scope.

Length of growing season is modulated by Northern Hemisphere jet stream variability

AbstractAtmospheric circulations create regions of similar climate at the land surface across the Northern Hemisphere's mid‐latitudes, while climate controls on plant phenology phases (phenophases) can vary. Here, we quantify and classify the seasonal impacts of the Northern Hemisphere jet stream (NHJ) on vegetation phenophases using novel NHJ indices, designed to characterize latitudinal jet stream position, and satellite‐based vegetation phenology products of length, start, and end of season (LOS, SOS, EOS). We composited years of northern and southern NHJ anomalies in April–May and October–November from LOS, SOS, and EOS and classified ecosystem response based on: latitudinal location relative to the climatological mean (CM) latitude of the NHJ; climate; and land cover type. For nearly a third of the NH, LOS was modulated by NHJ position. The magnitude and direction of NHJ influence on LOS was dependent on the season of NHJ position anomaly. In spring, a northern NHJ, which typically corresponded with warmer temperatures, led to earlier SOS and longer LOS, especially in cold systems north of the NHJ's CM. Surprisingly, in fall, a northern NHJ led to shorter LOS and earlier EOS for most systems, which may be due to the interaction of temperature and water availability in this season when water is critical for sustained growth. Southern NHJ corresponded with similar but opposite effects on phenophases. Crop land cover was mixed in LOS response to NHJ, reflecting the added impact of land‐use and management. The NHJ can synchronize phenology across apparently disparate regions of the Northern Hemisphere. Rather than simply lengthening or shortening seasons as the NHJ moves northward or southward, the influence of the NHJ on phenology at a given location depends on whether the NHJ is limiting resources—which vary relative to the climatological mean. We find that complex patterns in phenology emerge from a relatively simple contingency.

Management of Pediatric Lyme Disease: Updates From 2020 Lyme Guidelines.

Management of Pediatric Lyme Disease: Updates From 2020 Lyme Guidelines.