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Coronavirus disease 2019 (COVID-19) is a viral infection that causes various respiratory, gastrointestinal, and vascular symptoms. The acute illness phase lasts for about 2-3 weeks. However, there is increasing evidence that a percentage of COVID-19 patients continue to experience long-lasting symptoms characterized by fatigue, dyspnea, myalgia, exercise intolerance, and sleep disturbances, difficulty concentrating, anxiety, fever, headache, malaise, and vertigo. Similar symptoms are reported by patients who having myalgic encephalomyelitis/ chronic fatigue syndrome (ME/CFS). ME/CFS pathology is not known: it is thought to be multifactorial, resulting from the dysregulation of multiple systems in response to a particular trigger. There is a resemblance between post-acute COVID-19 symptoms and ME/CFS. However, at present, there is inadequate evidence to establish COVID-19 as an infectious trigger for ME/CFS. Further research is required to determine the natural history of this condition, as well as to define risk factors, prevalence, and possible interventional strategies. Keywords: chronic fatigue syndrome, COVID-19, human coronavirus, myalgic encephalomyelitis, post-infectious fatigue, review.

The new coronavirus has had a multifaceted impact on humans and has affected nearly everyone, some more than the other. The elderly is one such population, which has been hit in various ways. They are a vulnerable group of being the frequent victim of the infection and also getting succumbed to it. In addition, the mental health issues posed by the effect of this pandemic and the measures adopted to curb its spread have taken a toll and probably would continue long after this is over. In the scenario, with respect to geriatric mental health, emphasis may be made on individual and societal responsibilities rather than solely depending on the specialized mental health-care services. This article observes the vulnerabilities and mental health issues of the elderly in relation to this pandemic and possible measures at various levels.

Seasonally polyphenic types have been documented in many Drosophilids, which differ significantly during thermal stress. Although Drosophila simulans is a sibling species to Drosophila melanogaster, both thrive in the temperate and tropical climates, but various climatic factors are expected to impact their distribution and abundance. As a result, D. simulans may use phenotypic plasticity to adapt to colder and drier circumstances in temperate zones, although such studies are less known. In the present study, our main aim was to find a link between adaptive plasticity and thermal tolerance in D. simulans. We characterized two morphs in D. simulans flies based on the abdominal melanization collected from the same locality and season, as this trait is highly associated with the larval developmental conditions. Our results suggested that flies reared from dark and light morph showed significant differences in the basal level of proline, carbohydrates (trehalose, glycogen), and lipids (cuticular lipids and total body lipids) within simulated seasons and morph lineages in D. simulans flies. We further showed that D. simulans reared from dark morph are better adapted to cold conditions, whereas light flies are more adapted to warm conditions. The flies, both from light and dark morph lineages, when reared at 15 °C, showed an increase in the level of total body lipids after acclimation at 0 °C but a decrease in the level of proline and carbohydrates (trehalose, glycogen). Heat acclimation increases glycogen levels in the flies from light morph lineage while decreases trehalose and proline.

Narrow distribution patterns of tropical Drosophila species are limited by lower resistance to cold or drought. In the invasive tropical Drosophila kikkawai, we tested whether developmental and adult acclimations at cooler temperatures could enhance its stress resistance level. Adult acclimation of winter collected body color morphs revealed a significant increase in the level of cold resistance. For light morph, its abundance during winter is not consistent with thermal-melanism hypothesis. However, higher cold acclimation capacity, as well as storage of energy metabolites could support its winter survival. In the wild-caught light and intermediate morphs, there is a lack of trade-off between cold and heat resistance but not in the case of dark morph. Developmental plasticity (15°C) resulted in the fivefold increase of cold survival at 0°C; and a twofold increase in desiccation resistance but a modest reduction (∼28–35%) in heat resistance as compared to morph strains reared at 25°C. Drought acclimation changes were significantly higher as compared with cold or heat pretreatment. We observed a trade-off between basal resistance and acclimation capacity for cold, heat, or drought resistance. For homeostatic energy balance, adult acclimation responses (cold versus drought; heat versus drought) caused compensatory plastic changes in the levels of proline or trehalose (shared patterns) but different patterns for total body lipids. In contrast, rapid cold or heat hardening-induced changes in energy metabolites were different as compared to acclimation. The ability of D. kikkawai to significantly increase stress tolerance through plasticity is likely to support its invasion potential., Summary: In body color morphs of tropical Drosophila kikkawai, plasticity induced a higher level of resistance to cold and drought as well as three energy metabolites, which are likely to support its invasive potential.

In this paper we establish convergence and stability results using general contractive condition, quasi-nonexpansive mapping and mean non expansive mapping for K-iteration process. We shall also generalize the K-iteration process for a pair of distinct mappings and with the help of example we claim that the generalized iteration process has better convergence rate than the K-iteration process for single mapping and some of the existing iteration processes. Suitable examples are given in the support of main results.

Autumn-collected flies of Himalayan Drosophila nepalensis differ in body color phenotypes (males more melanized relative to females) and in their behavior (males abundant in the open sites vs. shelters-seeking females). In contrast, winter-collected flies of both sexes are equally melanized and abundant in the open sites. We tested developmental and adult plasticity changes in cold or drought tolerance in D. nepalensis flies reared under winter or autumn simulated conditions. In D. nepalensis flies reared at 21 °C, male flies were more cold tolerant (as shown by shorter chill-coma recovery time and lower cold-shock mortality). Further, male flies also exhibited greater drought tolerance (increased levels of desiccation resistance, cuticular lipid mass, melanization, hydration level, and dehydration tolerance) as compared to females. We observed sex-specific differences in the adult plasticity responses due to rapid cold or drought hardening (RCH or RDH); and for the persistence of cold acclimation effects. RCH or RDH-induced changes in the level of proline accumulations are negatively correlated with a decrease in the chill-coma recovery time. Therefore, cold or drought hardening treatments are likely to influence cold tolerance through proline accumulation. Developmental acclimation and adult hardening responses revealed significant interaction effects between sexes and thermal treatments. Thus, sex-specific differences in morphological traits (body melanization and cuticular lipid mass) and physiological traits (adult plasticity changes in cold tolerance and proline accumulation) correlate with behavioral divergence (habitat usage) across sexes.

Plastic responses to multiple environmental stressors in wet or dry seasonal populations of tropical Drosophila species have received less attention. We tested plastic effects of heat hardening, acclimation to drought or starvation, and changes in trehalose, proline and body lipids in Drosophila ananassae flies reared under wet or dry season-specific conditions. Wet season flies revealed significant increase in heat knockdown, starvation resistance and body lipids after heat hardening. However, accumulation of proline was observed only after desiccation acclimation of dry season flies while wet season flies elicited no proline but trehalose only. Therefore, drought-induced proline can be a marker metabolite for dry-season flies. Further, partial utilization of proline and trehalose under heat hardening reflects their possible thermoprotective effects. Heat hardening elicited cross-protection to starvation stress. Stressor-specific accumulation or utilization as well as rates of metabolic change for each energy metabolite were significantly higher in wet-season flies than dry-season flies. Energy metabolite changes due to inter-related stressors (heat versus desiccation or starvation) resulted in possible maintenance of energetic homeostasis in wet- or dry-season flies. Thus, low or high humidity-induced plastic changes in energy metabolites can provide cross-protection to seasonally varying climatic stressors., Summary: In the tropical Drosophila ananassae, low or high humidity-induced plastic changes in energy metabolites provide cross-protection to seasonally varying climatic stressors.

Some insect taxa from polar or temperate habitats have shown cross-tolerance for multiple stressors but tropical insect taxa have received less attention. Accordingly, we considered adult flies of a tropical drosophilid-Zaprionus indianus for testing direct as well as cross-tolerance effects of rapid heat hardening (HH), desiccation acclimation (DA) and starvation acclimation (SA) after rearing under warmer and drier season specific simulated conditions. We observed significant direct acclimation effects of HH, DA and SA; and four cases of cross-tolerance effects but no cross-tolerance between desiccation and starvation. Cross-tolerance due to heat hardening on desiccation showed 20% higher effect than its reciprocal effect. There is greater reduction of water loss in heat hardened flies (due to increase in amount of cuticular lipids) as compared with desiccation acclimated flies. However, cross-tolerance effect of SA on heat knockdown was two times higher than its reciprocal. Heat hardened and desiccation acclimated adult flies showed substantial increase in the level of trehalose and proline while body lipids increased due to heat hardening or starvation acclimation. However, maximum increase in energy metabolites was stressor specific i.e. trehalose due to DA; proline due to HH and total body lipids due to SA. Rapid changes in energy metabolites due to heat hardening seem compensatory for possible depletion of trehalose and proline due to desiccation stress; and body lipids due to starvation stress. Thus, observed cross-tolerance effects in Z. indianus represent physiological changes to cope with multiple stressors related to warmer and drier subtropical habitats.

This study investigates the effect of electric discharge machining (EDM) process parameters [current, pulse-on time (Ton), pulse-off time (Toff) and electrode material] on material removal rate (MRR), electrode wear rate (EWR) and surface roughness (SR) during machining of aluminum boron carbide (Al–B4C) composite. This article also summarizes a brief literature review related to aluminum metal matrix composites (Al-MMCs) based on different process and response parameters, work and tool material along with their sizes, dielectric fluid and different optimization techniques used. The MMC used in the present work is stir casted using 5% (wt) B4C particles of 50 micron size in Al 6061 metal matrix. Taguchi technique is used for the design of experiments (L9-orthogonal array), while the experimental results are analyzed using analysis of variance (ANOVA). Response table for average value of MRR, EWR and SR shows that current is the most significant factor for MRR and SR, while electrode material is mo...

The paper analyze the role of rural tourism for the development of rural areas, The study analyzed how the different types of tourist product diversifications influence the development possibilities of studied rural areas in India. The government should sponsor private Sector to promote tourism in rural areas. For upgrading the rural tourism government requires to understand the rural location, demography, socio-culture, financial and political background of that area. How we can involve the rural citizens to improve their socio-economic condition. The objective of this paper is to present an update on rural tourism expansion and development in India. Rural tourism is rising in terms of number of visitors and the government of India should focus on it as an engine of growth

Insects in tropical wet or dry seasons are likely to cope with starvation stress through plastic changes (developmental as well as adult acclimation) in energy metabolites. Control and experimental groups of

Cross-tolerance effects for cold and drought stressors are well known for temperate and polar ectothermic organisms. However, less attention has been paid to plastic changes induced by wet-dry conditions for the tropical insect taxa. Drosophila ananassae is abundant in wet habitats but its desiccation sensitivity is likely to make it vulnerable under expected drought conditions due to climate change. We tested plastic effects of heat hardening, acclimation to drought or starvation; and changes in trehalose, proline and body lipids in D. ananassae flies reared under wet or dry season specific conditions. Wet season flies showed significant increase in heat knockdown, starvation resistance and body lipids after heat hardening. However, accumulation of proline was observed only after desiccation acclimation of dry season flies while wet season flies elicited no proline but trehalose only. Thus, drought induced proline can be a marker metabolite for dry season flies. Further, partial utilization of proline and trehalose under heat hardening reflects their possible thermoprotective effects. Heat hardening elicited cross-protection to starvation stress. Stressor specific accumulation or utilization as well as rates of metabolic change for each energy metabolite were significantly higher in wet season flies than dry season flies. Energy budget changes due to inter-related stressors (heat vs desiccation or starvation) resulted in possible maintenance of energetic homeostasis in wet or dry season flies. Thus, low or high humidity induced plastic changes in energy metabolites can provide cross-protection to seasonally varying climatic stressors.Summary statementIn the tropical Drosophila ananassae, low or high humidity induced plastic changes in energy metabolites provide cross-protection to seasonally varying climatic stressors

In the Western Himalayas,Drosophila nepalensisis more abundant during the colder and drier winter than the warmer rainy season but the mechanistic bases of such adaptations are largely unknown. We tested effects of developmental plasticity on desiccation-related traits (body size, body melanization and water balance traits) that may be consistent with changes in seasonal abundance of this species.D. nepalensisgrown at 15°C has shown twofold higher body size, greater melanization (∼15-fold), higher desiccation resistance (∼55 h), hemolymph as well as carbohydrate content (twofold higher) as compared with corresponding values at 25°C. Water loss before succumbing to death was much higher (∼16%) at 15°C than 25°C. Developmental plastic effects on body size are associated with changes in water balance-related traits (bulk water, hemolymph and dehydration tolerance). The role of body melanization was evident from the analysis of assorted darker and lighter flies (from a mass culture ofD. nepalensisreared at 21°C) which lacked differences in dry mass but showed differences in desiccation survival hours and rate of water loss. For adult acclimation, we found a slight increase in desiccation resistance of flies reared at lower growth temperature, whereas in flies reared at 25°C such a response was lacking. InD. nepalensis, greater developmental plasticity is consistent with its contrasting levels of seasonal abundance. Finally, in the context of global climate change in the Western Himalayas,D. nepalensisseems vulnerable in the warmer season due to lower adult as well as developmental acclimation potential at higher growth temperature (25°C).

The role of melanization and cuticular lipids in water conservation has been studied in many Drosophila species (Diptera: Drosophilidae). Nevertheless, a comparative approach to larval and adult stages of ecologically diverse, wild Drosophila species is still required. Based upon abdominal cuticular melanization patterns, wild-caught Drosophila species were categorized as (1) melanic, (2) fixed-melanic, or (3) non-melanic. At the interspecific level, the ecological significance of melanization and cuticular lipids was determined by the inverse association of melanization and cuticular water loss in melanic species, and of cuticular lipids and cuticular water loss in fixed-melanic and non-melanic species. Interestingly, higher amounts of cuticular lipids were also evident in fixed as well as non-melanic species, as compared to melanic species at larval stages, which is consistent with their differences in reduced water loss rates. Moreover, fixed-melanic and non-melanic species exhibited comparatively higher (ca. 1.8–2.0 fold) desiccation resistance. Thus, cuticular lipids provide a better waterproofing mechanism than melanization. Furthermore, acclimation to dehydration stress in adults improved desiccation resistance in melanic species, whereas such effects were lacking in fixed-melanic and non-melanic species. However, there were no changes in cuticular components as a consequence of desiccation acclimation. Thus, our results indicate that melanic, fixed-melanic, and non-melanic Drosophila species differ in the evolved physiological mechanisms of water conservation to adapt to dry conditions.

We investigated associations of the species specific divergence of thermal adaptations of Drosophila nasuta and Drosophila immigrans with seasonal as well as geographical changes in the relative abundance. In D. immigrans, cold resistance and egg-to-adult viability after a cold-shock have shown a positive cline with latitude, whereas no such clinal patterns were evident for heat resistance as well as egg-to-adult viability after heat stress. In contrast, basal heat tolerance and egg-to-adult viability after a heat-shock increased towards the equator i.e. from north to south in D. nasuta. Further, we also found species-specific divergence in seasonal climatic selection responses for heat as well as cold resistance i.e. warmer and higher humidity conditions of the rainy season have evidenced ∼2-fold higher heat tolerance of D. nasuta, but lower temperature as well as lower humidity conditions of the autumn significantly increased (∼3-fold) cold tolerance of D. immigrans. Geographical variations were significant for the absolute and relative hardening capacity for cold tolerance in D. immigrans, but for heat resistance of D. nasuta. Results of multiple regression analysis of changes in thermal tolerance level in latitudinal populations as a simultaneous function of climatic variables (Tave and RH) have shown that average yearly relative humidity levels significantly affect heat tolerance of D. nasuta, but both Tave and RH contribute to changes in the cold tolerance of D. immigrans. Thus, our results suggest that climatic selection responses for basal and hardened thermo-tolerance levels affect relative abundance of D. nasuta and D. immigrans across a latitudinal transect as well as seasons.

The average temperature of the earth has increased from 0.3 to 0.6 °C, and warming is facilitating faunal reshuffling. Variable thermal environments warrant mechanisms to adjust the expression of phenotypic values to environmental needs. Ectothermic Drosophilids are profoundly affected by thermal selection (i.e., genetic effects) or through induced effects on phenotypes (i.e., plastic effects). Climatic data for the last fifty years involves a significant change in average temperature (Tave) of Western Himalayas, which has affected the distribution and boundaries of various Drosophilids in this region. There is a significant decline in the number of D. nepalensis from lower ranges; whereas D. ananassae is reported to be introduced to lower to mid mountainous ranges. Further, a comparison of fecundity, hatchability, and viability at different growth temperatures has shown significant decrease in trait values at 17 °C in D. ananassae and at 25 °C in D. nepalensis. Thus, the recent range changes of these two species involve genetic effects on ecophysiological and plastic effects on life history traits. Our results indicate that thermal plasticity of life history traits can be species-specific; thus climate change may lead to a mismatch of such traits to the changing environment. We suggest that D. nepalensis and D. ananassae could serve as indicator species for analyzing range changes under changing climatic conditions. Evolutionary biologists can provide unique perspective to the examination of how climate change will affect the earth's biota.

The Indian subcontinent shows high levels of seasonal weather variation, but the extent to which mating-related traits (mating latency, copulation duration and number of progeny produced) are being affected by such variations in Drosophila species remain poorly understood. In the present study, we analyzed the effects of seasonal change (humidity and temperature) on mating-related traits of Drosophila melanogaster by mimicking natural conditions in the laboratory. The light body color phenotype is collected in large numbers during the rainy season, while the dark phenotype is prevalent in the winter. We found that a short-term stress, in the form of reduced humidity or temperature, causes a strong climatic selection pressure, which leads to assortative mating and longer copulation duration of the dark phenotype. By contrast, the light phenotype shows higher assortative mating and longer copulation duration after short-term high humidity or high temperature stress. Higher assortative mating and increased copulation duration results in high progeny numbers which may be a cause for the high prevalence of the dark phenotype in winter and the light phenotype in the rainy season. Thus, besides plasticity, seasonal changes in mating propensity can be a potential cause of the change in the frequency of the dark and light phenotypes of D. melanogaster during different seasons.

Altitudinal localities of the northern India are associated with high seasonal changes. Drosophila melanogaster flies are darker during the winter season as compared to the autumn season. We tested the hypothesis whether there are altitudinal clines for mating related traits. We observed negative cline for mating latency and positive for copulation period along altitude in D. melanogaster. We further tested if seasonally varying body melanisation is correlated with mating propensity in D. melanogaster. Thus, we examined the D. melanogaster flies collected during autumn and winter season for changes in body melanisation and mating-related traits. Flies from the winter season show high melanisation, copulation duration and fecundity/day as compared to the autumn season flies. By contrast mating latency is longer during autumn as compared to winter season. Based on within- and between-population analysis, body melanisation shows positive correlation with copulation duration and fecundity/day, while negative correlation with mating latency. Within-population analyses show no correlation between body size and ovariole number with body melanisation. Thus, our data suggest that seasonal changes in body melanisation are correlated with mating latency, copulation duration and fecundity/day, but no correlation with body size and ovariole numbers. Further, we observed that seasonal changes in these clines, although have some component of plasticity, have strong genetic basis as the seasonal and population differences were maintained for various traits after 8 generations in the laboratory.

In this paper, we prove strong and weak convergence results of modified Ishikawa iterative process to common fixed points of two nearly lipschitzian mappings in the framework of hyperbolic spaces.Our results extend and improve results of (4) and (11) from uniformly convex Banach spaces and CAT (0) spaces to hyperbolic spaces.

Seasonally varying populations of ectothermic insect taxa from a given locality are expected to cope with simultaneous changes in temperature and humidity through phenotypic plasticity. Accordingly, we investigated the effect of saturation deficit on resistance to desiccation in wild-caught flies from four seasons (spring, summer, rainy and autumn) and corresponding flies reared in the laboratory under season-specific simulated temperature and humidity growth conditions. Flies raised under summer conditions showed approximately three times higher desiccation resistance and increased levels of cuticular lipids compared with flies raised in rainy season conditions. In contrast, intermediate trends were observed for water balance-related traits in flies reared under spring or autumn conditions but trait values overlapped across these two seasons. Furthermore, a threefold difference in saturation deficit (an index of evaporative water loss due to a combined thermal and humidity effect) between summer (27.5 mB) and rainy (8.5 mB) seasons was associated with twofold differences in the rate of water loss. Higher dehydration stress due to a high saturation deficit in summer is compensated by storage of higher levels of energy metabolite (trehalose) and cuticular lipids, and these traits correlated positively with desiccation resistance. In Z. indianus , the observed changes in desiccation-related traits due to plastic effects of simulated growth conditions correspond to similar changes exhibited by seasonal wild-caught flies. Our results show that developmental plastic effects under ecologically relevant thermal and humidity conditions can explain seasonal adaptations for water balance-related traits in Z. indianus and are likely to be associated with its invasive potential.