NAEA News, Volume 63, Number 2, April–May 2021

BackgroundSocial distancing was the predominant strategy used to mitigate the spread of Coronavirus disease 2019 (COVID‐19) at the start of the COVID‐19 pandemic.AimsTo study the impact of social distancing on the incidence of bacteraemia. The number of admitted patients with positive blood cultures in April–May 2020 in one tertiary medical centre was compared with the number during the same period in the previous 3 years (April–May 2017–2019).MethodsRetrospective review of all positive blood cultures from January to July in the years 2017–2020.ResultsThere were fewer cases of Streptococcus bacteraemia as well as coagulase‐negative Staphylococcus bacteraemia and other possible contaminated blood cultures in April–May 2020. Compared with the previous 3 years, the incidence of Streptococcus pneumoniae bacteraemia among all bacteraemias was lower in April–May 2020 (5%) than in 2017–2019 (12.0%; 95% confidence interval 10.3–14.1%). In general, fewer cases of bacteraemia caused by oropharynx organisms were observed in April–May 2020; only 6 cases versus 31 (95% confidence interval 10–53) during the same period in 2017–2019. Only one case of S. pneumoniae bacteraemia was observed in April–May 2020 and its percentage among all bacteraemias was lower in April–May 2020 (0.4%) than during the same period in 2017–2019 (3.3%).ConclusionThe incidences of streptococcal bacteraemia and bacteraemia of organisms transmitted through respiratory secretions were lower when there were social distancing restrictions. Adopting measures of social distancing may decrease the morbidity from bacteraemia caused by oropharynx and respiratory bacteria.

A linear regression model is constructed to predict the April–May precipitation in central China (PCC) with a lead time of 1–2 months. This model not only reproduces the historical April–May PCC from 1985 to 2006 but also demonstrates strong robustness and reliability during the independent test period of 2007–16. Two preceding factors are selected to build the model, the February–March Arctic stratospheric ozone (ASO) and Indian Ocean sea surface temperature (IOSST), indicating a synergistic impact of Arctic and tropical signals on the midlatitude climate. A possible mechanism of ASO changes affecting Chinese precipitation is that the stratospheric circulation anomalies related to ASO changes may downward influence circulation over North Pacific, and then extend westward to influence East Asia, leading to changes in Chinese precipitation. Anomalies of the other predictor, IOSST, are associated with a baroclinic structure over central China. For example, warm IOSST causes anomalous convection over central China and affects the warm and humid airstream flowing from the Pacific to China. These processes related to the two predictors result in the April–May PCC anomalies. Sensitivity experiments and a transient experiment covering a longer period than the observations/reanalysis support the results from our statistical analysis based on observations. It implies that this statistical model could be applied to the output of seasonal forecasts from observations and improve the forecasting ability of April–May PCC in the future.

ABSTRACTInevitable drawbacks occur when the Asian monsoon is simulated at a horizontal resolution that is too low to resolve topographic effects and sub‐grid processes. By comparing the Coupled Model Intercomparison Project (CMIP) phase 5 simulations conducted at higher (∼1°) and lower (∼3°) horizontal resolutions, this study attempted to extend understanding of potential resolution limits in simulating the East Asian presummer climate. April–May is found to have considerable resolution‐dependent contrasts in position and strength of precipitation (spring rains and pre–Meiyu) among the simulations. The low‐resolution models cannot simulate ascending vertical motion over the mountainous regions in the southern Tibetan Plateau and subtropical East Asia, which coincides with the overestimation of the strength of the lower‐tropospheric westerly in 90°–105°E and of the downstream southerly in 110°–130°E. Because of the southerly wind bias, the East Asian presummer precipitation simulated in the low‐resolution models is lower in amount and located farther north compared with the observed and high‐resolution models. Despite distinct large‐scale climatology between April and late May, the East Asian precipitation contrasts in these two periods are similar between the high‐ and low‐resolution models, which could be possibly explained as a systematic response to resolution. Systematically less precipitation in the high‐resolution model compared with the low‐resolution model is also observable over the Maritime Continent, whereas a further connection to the East Asian precipitation simulation remains unclear. Regarding projected changes, the resolution‐dependent contrasts are also considerable; the contrasts further suggest potential regional interactions such as between the subtropical South and East Asia (10°–20°N).

The availability of seasonally abundant energy-rich prey can be a significant factor for the survival and reproductive success of predator populations. Large numbers of Steller sea lions (Eumetopias jubatus) were attracted to a prespawning aggregation of eulachon (Thaleichthys pacificus) in Berners Bay in southeast Alaska during April–May in 2002 and 2003. Sea lion abundance increased as eulachon gathered in Berners Bay, peaked as eulachon abundance peaked, and decreased as the eulachon moved up-river. As sea lion abundance increased in Berners Bay, sea lion abundance decreased at Benjamin Island, a sea lion haulout located 22 km away. The eulachon provided an abundant, energy-rich, predictable prey source for the Steller sea lions: (i) eulachon energy density was 9.70 ± 0.24 kJ·g–1, much higher than that of any forage species reported in the North Pacific Ocean except northern lampfish (Stenobrachius leucopsarus); (ii) a large surplus of prey was available per sea lion while the eulachon aggregation was present; and (iii) the spawning run usually begins between late April and early May. The eulachon pulse may be critical to Steller sea lions during a period of high energetic demands.

The relative contribution of tillers present in April and those appearing in consecutive periods in spring was assessed for perennial ryegrass cultivars in the three maturity groups (early, intermediate‐ and late‐heading). Each group was represented by two diploid and one tetraploid cultivar each in plots in their third (2000) and fourth (2001) harvest years in three replicated blocks receiving an average of 325 kg N ha−1 and cut seven (in 2001) or eight (in 2000) times annually. ‘Main’ tillers and their daughters were marked with colour‐coded PVC‐covered wire loops in early April as were daughters which appeared in consecutive periods between harvests, the loop colour identifying the period of origin of the tiller. Tillers were harvested at cutting height (5 cm) before the plots were harvested and the herbage from tillers with the same colour code bulked per plot. Tillers were identified retrospectively as ‘reproductive’ if they had been decapitated at the previous harvest.Dry‐matter yield was higher in the early than late‐heading cultivars in April and early May but this was reversed in harvests in late May and June. The early heading group had a lower lamina content than the late‐heading group during reproduction growth, both due to the reproductive tillers (mainly those which overwintered) having a lower leaf content and to their being fewer and smaller vegetative tillers during the reproductive phase than for the late‐heading group.Turnover of tillers was high in spring due to decapitation of reproductive tillers and rapid post‐flowering tillering. This was particularly pronounced in the early heading group which also had slightly more tillers marked in April which were subsequently decapitated than in the other maturity groups, i.e. 0·56 compared with 0·44 for the late‐maturing group. Mean ratios of rate of death: rate of tillering for 3 years (1999–2001) for the early and late‐heading groups were 0·8 and 0·4, respectively, for April–May and 1·1 and 2·4, respectively, for June indicating the different patterns in tiller turnover for the two extreme maturity groups. Information on tiller origin and contribution to yield can be used to refine tiller‐based grass growth models.

Sorghum bicolor (L.) Moench is the fifth most valuable cereal crop globally. Although sorghum is tolerant to drought and elevated temperatures, it is susceptible to chilling, frost, and freezing stresses. Sorghum seeds planted in April may encounter frequent frost during late April and early May. Early spring freezing temperatures adversely affect crop development and yield. This study aims to identify genomic regions associated with frost tolerance at the seedlings stage. Breeding freeze-tolerant cultivars require selection for freeze tolerance in nurseries. However, the unpredictability of environmental conditions complicates the identification of freeze-tolerant genotypes. An indoor selection protocol has been developed to investigate the genetic determinism of freeze tolerance at the seedling stages and its correlation with several developmental traits. To accomplish this, we used two populations of recombinant inbred lines (RIL) developed from crosses between cold-tolerant (CT19, ICSV700) and cold-sensitive (TX430, M81E) parents. The derived RIL populations were evaluated for single nucleotide polymorphism (SNP) using genotype-by-sequencing (GBS) under controlled environments for their response to freezing stress. Linkage maps were constructed with 464 and 875 SNPs for the CT19 X TX430 (C1) and ICSV700 X M81E(C2) populations. Using quantitative trait loci (QTL) mapping, we identified six QTLs conferring tolerance to freezing temperatures. One QTL in the C1 population and four QTLs in the C2 population, explain 17.75-98% of the phenotypic variance of traits measured. Proline leaf content was increased in response to exposing the seedlings to low temperatures. Candidate QTLs identified in this study could be further exploited to develop frost-tolerant cultivars as proxies in marker-assisted breeding, genomic selection, and genetic engineering.

Dendroclimatic Reconstruction of April–May Temperature Fluctuations in the Western Himalaya of India Since A.D. 1698

A study by Durga Prasad and Ambily observed an anomalous decrease in the lunar surface temperatures during the period April–May 2020, which they then attributed to the anthropogenic effects of the COVID-19 global lockdown effect. We have re-examined their data and while the anomalous decrease in the lunar surface temperature during April–May 2020 appears in our analysis as well, so does another significant dip in early 2018. Furthermore, the decline to the minimum observed during April–May 2020 is seen to begin in 2019, that is, quite some time before the COVID-19 event that led to the global lockdown and the suggested anthropogenic effect of reduced pollution. We, therefore, conclude that one cannot attribute the effects of the observed changes in the lunar surface temperature during April–May 2020 directly and unambiguously to reduced human activity during the COVD-19 lockdown as claimed by Durga Prasad and Ambily.

The potential of rearing the red seaweed Mastocarpus stellatus (Stackhouse) Guiry, a carrageenophyte, as a biofilter in a pilot-scale, integrated multi-trophic aquaculture (IMTA) system was investigated. From April to June, M. stellatus, collected from a population in the north of Portugal was cultivated in 1200-L tanks in two consecutive, 4-week experiments with nutrient-enriched waters derived from fish tanks. The stocking density of 3 kg m−2 provided the best yields, ranging from 29.6 g dw m−2 day−1 in April–May to 38.9 g dw m−2 day−1 in June. In the April–May period, a linear increase in the yields was found at higher densities. M. stellatus growth rates during April–May period did not diverge significantly between stocking densities and reached a mean relative growth rate of 3.09 ± 0.90 % day−1 in April–May and 4.02 ± 0.43 % day−1 in June at 3 kg m−2. In June, the increase in stocking density negatively affected the growth rates (3 < 2 < 1 kg m−2). M. stellatus used ammonium (TAN) as the main N source and the nutrient uptake efficiency was found to be similar between stocking densities, but highest in June. The seaweeds removed an average of 66.29 ± 3.57 μmol TAN L–1 in May and 84.49 ± 4.00 μmol TAN L–1 in June, which corresponded to the mitigation of 43.19 ± 1.61 and 49.00 ± 1.59 % of NH3 from the system, respectively. This study demonstrated the potential to effectively cultivate M. stellatus in an IMTA system.

Human activities such as dam construction can lead to significant river flow regime changes and, consequently, river environments and habitats. Different approaches for estimating the environmental flow have developed to improve the river ecosystem's environmental and habitat conditions. The hydrological approach is considered in many studies to estimate environmental flows considering its advantages. Vimba vimba persa is an economically and ecologically valuable species in the Caspian Sea that spawns and reproduces naturally in the Gorganrood River downstream in April–May. After the construction of the Voshmgir dam on the Gorganrood River, the fish population has drastically reduced in recent decades. In this study, to investigate the effect of constructing the Voshmgir dam on the environmental flow of Gorganrood River, a wide range of hydrological methods, including Tennant, Tessman, Arkansas, Aquatic Base Flow, Flow Duration Curve, High Flow-Low Flow, and FDC Shifting have been used. Comparing the correlation between the mean monthly flow time series before and after the Voshmgir dam demonstrates remarkable changes, including Pearson (0.95 to 0.86), Spearman's rho (0.93 to 0.78), and Kendall's τ (0.78 to 0.61) as a consequence of dam construction. The results indicate that estimated environmental flow from Tennant (1.1, 3.4 to 1.3, 3.8 cms) and Aquatic Base Flow (0.5 to 1.8 cms) methods have led to inadequate estimation due to significant changes in flow in different months. The amount of environmental flow during April–May estimated from investigated methods indicates the dam negatively affected water allocation to meet the river downstream's ecological and environmental needs. The flow duration curve analysis confirms that the dam construction has caused the river flow to fluctuate significantly within the year. The dam construction has dramatically reduced the flow in April–May, a critical environmental and ecological season. The April–May period coincides with the river's flood season. The construction of the Voshmgir dam has caused the components of high flow in the environmental flow to face severe shortages.

Fewer follicles and of variable size are found at any time on the mare ovary compared with other livestock species, also influenced by seasonal variation. This is reflected on the population of cumulus–oocyte complexes (COC) collected that is characterised by a high heterogeneity. Recovered immature oocytes presumably need different culture conditions. The main factors contributing to this high heterogeneity are the follicle diameter, the status of the cumulus oophorus, and the reproductive seasonality. Therefore, the aim of the present study was to assess the nuclear chromatin configuration and the oocytes–cumulus cell gap junction-mediated communication (GJC) functionality in COC of different origins because these parameters are indicative of the oocyte’s metabolic state and should be taken into account when designing IVM strategies. The COC with compact (Cp) or expanded (Ex) cumulus oophorus were collected from follicles of different diameters (&lt;1, 1–2, and &gt;2 cm) in October–November, January–February, and April–May. The GCJ functionality was assessed by Lucifer Yellow microinjection and chromatin configuration was evaluated by Hoechst and Lacmoid staining, after cumulus cells removal. Data were obtained from a total of 1003 oocytes and were analysed by chi-squared test. Overall, GJC functionality was impaired in the majority of Ex COC in each follicle category, even though a certain proportion of them had open GJC (% of Ex COC with open GJC was 39.7, 29.3, and 39.3 in &lt;1, 1–2, and &gt;2 cm follicles, respectively). Moreover, the proportion of Ex COC with open GJC did not differ significantly between periods (% of Ex COCs with open GJC in October–November, January–February, and April–May was, respectively, 43.3, 28.6, and 41.7 in &lt;1 cm follicles; 45.5, 19.3, and 26.47 in 1–2 cm follicles; 66.7, 50, and 16.7 in &gt;2 follicles). On the contrary, the majority of Cp COC from follicles &lt;1 and 1–2 cm, showed open GCJ in October–November and April–May, whereas they decreased significantly in January–February. This tendency was not maintained in Cp COC from follicles &gt;2 cm, where GJC functionality did not differ significantly between periods (% of Cp COC with open GJC in October–November, January–February, and April–May was, respectively, 74.4, 35.7, and 75 in &lt;1 cm follicles; 73.8, 42.1, and 67.7 in 1–2 cm follicles; 58.3, 58.3, and 68.6 in &gt;2-cm follicles). Chromatin configuration analysis revealed that the highest proportion (23.9%) of oocytes with fibrillar chromatin was found in Cp oocytes from &lt;1 cm follicles, whereas the proportion of oocytes with fibrillar chromatin ranged from 5.4 to 12.5% in the other groups. Moreover, the increase in follicle diameter was generally associated with an increase of chromatin condensation in Cp COC. Interestingly, the chromatin configuration distribution did not differ significantly among seasons. Our data could be useful in setting up new in vitro cultural strategies aimed to improve horse-assisted reproductive technology efficiency as well as in the understanding of horse oocyte biology. Funding: Grant no. 26096200 ‘Ex Ovo Omnia’ from Regione Sardegna &amp; Lombardia and ‘Dote Ricerca Applicata’ (VL and IT).

Over the Indian region, the pre-monsoon (i.e. April–May) is a dry summer season. The heatwaves, as well as local temperature variations during this season, are not associated with significant large-scale convective heating like the monsoonal modes, and several studies identified several drivers of heatwaves. Heatwaves are extreme events. Are these extremes arising from low-frequency intraseasonal modes, in the same way, extreme rainfall occurs on a synoptic or intraseasonal mode during monsoon? Studies do not explicitly point out the existence of temperature intraseasonal modes during April–May over the Indian region, and it is not clear if some of the drivers of heatwaves can also explain the April–May temperature variations as derivative of some modes. This study identifies the dominant pair of the intrinsic mode of temperature intraseasonal oscillations, which can also explain the heatwave spikes. The empirical orthogonal function based modes are isolated in the detrended surface temperature data to remove the global warming mode. It was found that the subtropical jet acting as a Rossby wave guide drives the first mode with pan India spatial modal signature, while the second mode is driven by the extratropical Rossby wave modes originating from the latitudes of the eddy-driven jet. Another important result is that the first (second) mode principal component shows a significant decreasing (increasing) trend from 1981–2020 period. The observed spatial heterogeneity in warming and the trend in the spatial distribution of extreme temperature events in India could also be explained by the trend in the two modes of oscillation.

This study presents an experimental model for Seasonal Probabilistic Outlook for Tornadoes (SPOTter) in the contiguous United States for March, April, and May and evaluates its forecast skill. This forecast model uses the leading empirical orthogonal function modes of regional variability in tornadic environmental parameters (i.e., low-level vertical wind shear and convective available potential energy), derived from the NCEP Coupled Forecast System, version 2, as the primary predictors. A multiple linear regression is applied to the predicted modes of tornadic environmental parameters to estimate U.S. tornado activity, which is presented as the probability for above-, near-, and below-normal categories. The initial forecast is carried out in late February for March–April U.S. tornado activity and then is updated in late March for April–May activity. A series of reforecast skill tests, including the jackknife cross-validation test, shows that the probabilistic reforecast is overall skillful for predicting the above- and below-normal area-averaged activity in the contiguous United States for the target months of both March–April and April–May. The forecast model also successfully reforecasts the 2011 super-tornado-outbreak season and the other three most active U.S. tornado seasons in 1982, 1991, and 2008, and thus it may be suitable for an operational use for predicting future active and inactive U.S. tornado seasons. However, additional tests show that the regional reforecast is skillful for March–April activity only in the Ohio Valley and South and for April–May activity only in the Southeast and Upper Midwest. These and other limitations of the current model, along with the future advances needed to improve the U.S. regional-scale tornado forecast, are discussed.

Linkages among density, flow, and bathymetry gradients were explored at the entrance to the Chesapeake Bay with underway measurements of density and flow profiles. Four tidal cycles were sampled along a transect that crossed the bay entrance during cruises in April–May of 1997 and in July of 1997. The April–May cruise coincided with neap tides, while the July cruise occurred during spring tides. The bathymetry of the bay entrance transect featured a broad Chesapeake Channel, 8 km wide and 17 m deep, and a narrow North Channel, 2 km wide and 14 m deep. The two channels were separated by an area with typical depths of 7 m. Linkages among flows, bathymetry, and water density were best established over the North Channel during both cruises. Over this channel, greatest convergence rates alternated from the left (looking into the estuary) slope of the channel during ebb to the right slope during flood as a result of the coupling between bathymetry and tidal flow through bottom friction. These convergences were linked to the strongest transverse shears in the along-estuary tidal flow and to the appearance of salinity fronts, most markedly during ebb periods. In the wide channel, the Chesapeake Channel, frontogenesis mechanisms over the northern slope of the channel were similar to those in the North Channel only in July, when buoyancy was relatively weak and tidal forcing was relatively strong. In April–May, when buoyancy was relatively large and tidal forcing was relatively weak, the recurrence of fronts over the same northern slope of the Chesapeake Channel was independent of the tidal phase. The distinct frontogenesis in the Chesapeake Channel during the increased buoyancy period was attributed to a strong pycnocline that insulated the surface tidal flow from the effects of bottom friction, which tends to decrease the strength of the tidal flow over relatively shallow areas.

The spatial variation of temperature is found to depend linearly on climate continentality, morphology of the relief, the position of the site with respect to seas, in addition to the usual elevation, latitude and longitude predictors. There are other factors that can have an additional significant influence: big bodies of water, terrain attributes relief, atmospheric factors (local circulation), configuration and aspect of coasts and vegetation. Therefore, these multifactorial influences form the climatic field of temperature.&#x0D; In this study, the regional semi—empirical model of the spatiotemporal distribution of the average annual and monthly temperature for the plain part of Ukraine on the basis of the methodology for assessing the influence of height above sea level and geographic coordinates is proposed. Based on the method for determining the altitudinal, latitudinal, and longitudinal gradients of meteorological parameters, we calculated these gradients for annual and monthly air surface temperature for the periods 1961—1990 and 1991—2020.&#x0D; Thus, on the plain part of Ukraine, the annual surface air temperature decreases by an average on 0.60—0.63 °C with a shift of 100 m height above sea level, on 0.51—0.55 °C with a shift of one latitude degree to the north, on 0.067—0.071 °C with a shift of one longitude degree to the east. Also, the variations of these annual mean temperature gradients from year to year over the period 1991—2020 are characteristic.&#x0D; The seasonal variation of gradients has a pronounced non—monotonic character: highest values of altitudinal gradientare typical for July—August (from –0.63 to –0.73 °C per 100 m), and the lowest values — for April—May (from –0.45 to –0.55 °C per 100 m); highest values of latitudinal gradient are typical for August—September (from –0.60 to –0.70 °С per 1 °N), and the lowest values — for April—May (from –0.20 to –0.35 °С per 1° N); the longitudinal gradients have positive values in June—August (0.074—0.128 °C per 1° E), and negative values in November—March (from –0.228 to –0.154 °C per 1° E).&#x0D; We found that the altitudinal and latitudinal gradients of temperature have the most spatiotemporal variability and the longitudinal gradient has the smallest one. Greatest variabilities of temperature gradient values are typical for February—March and July—September, and the least variability — for April—May.&#x0D; The analysis of the dynamics of gradient changes in the period 1991—2020 compared to the period 1961—1991 showed the following: the altitudinal gradientvalues increased by 8—13 %. in January and March—May; the latitudinal gradient values increased by ~30 % in December—February and decreased by ~20 % in May—August.&#x0D; The proposed semi—empirical model contains a coefficient that takes into account influence of additional effects associated with pronounced orographic and other terrain features. This study presents the numerical values of this coefficient for some specific microclimate regions of the plain part of Ukraine.&#x0D; The model estimates of thirty—year monthly mean temperature in Ukraine for the periods 1961—1990 and 1991—2020was calculated. A comparison of the model estimates of of the average annual and monthly temperature for 72 meteostations in Ukraine with their actual values showed a statistically significant correlation (the reliability of the linear approximation is 0.89—0.98). Thus, the presented design of the semi-empirical model makes it possible to quite well restore the annual and monthly temperature on the territory of Ukraine