Intermittent Periods Research Articles

Remote ischaemic preconditioning - translating cardiovascular benefits to humans.

Remote ischaemic preconditioning (RIPC), induced by intermittent periods of limb ischaemia and reperfusion, confers cardiac and vascular protection from subsequent ischaemia–reperfusion (IR) injury. Early animal studies reliably demonstrate that RIPC attenuated infarct size and preserved cardiac tissue. However, translating these adaptations to clinical practice in humans has been challenging. Large clinical studies have found inconsistent results with respect to RIPC eliciting IR injury protection or improving clinical outcomes. Follow‐up studies have implicated several factors that potentially affect the efficacy of RIPC in humans such as age, fitness, frequency, disease state and interactions with medications. Thus, realizing the clinical potential for RIPC may require a human experimental model where confounding factors are more effectively controlled and underlying mechanisms can be further elucidated. In this review, we highlight recent experimental findings in the peripheral circulation that have added valuable insight on the mechanisms and clinical benefit of RIPC in humans. Central to this discussion is the critical role of timing (i.e. immediate vs. delayed effects following a single bout of RIPC) and the frequency of RIPC. Limited evidence in humans has demonstrated that repeated bouts of RIPC over several days uniquely improves vascular function beyond that observed with a single bout alone. Since changes in resistance vessel and microvascular function often precede symptoms and diagnosis of cardiovascular disease, repeated bouts of RIPC may be promising as a preclinical intervention to prevent or delay cardiovascular disease progression.

Observational Subseasonal Variability of the PM2.5 Concentration in the Beijing-Tianjin-Hebei Area during the January 2021 Sudden Stratospheric Warming.

It is still not well understood if subseasonal variability of the local PM2.5 in the Beijing-Tianjin-Hebei (BTH) region is affected by the stratospheric state. Using PM2.5 observations and the ERA5 reanalysis, the evolution of the air quality in BTH during the January 2021 sudden stratospheric warming (SSW) is explored. The subseasonal variability of the PM2.5 concentration after the SSW onset is evidently enhanced. Stratospheric circumpolar easterly anomalies lasted for 53 days during the January–February 2021 SSW with two evident stratospheric pulses arriving at the ground. During the tropospheric wave weakening period and the intermittent period of dormant stratospheric pulses, the East Asian winter monsoon weakened, anomalous temperature inversion developed in the lower troposphere, anomalous surface southerlies prevailed, atmospheric moisture increased, and the boundary layer top height lowered, all of which favor the accumulation of pollutant particulates, leading to two periods of pollution processes in the BTH region. In the phase of strengthened East Asian winter monsoon around the very beginning of the SSW and another two periods when stratospheric pulses had reached the near surface, opposite-signed circulation patterns and meteorological conditions were observed, which helped to dilute and diffuse air pollutants in the BTH region. As a result, the air quality was excellent during the two periods when the stratospheric pulse had reached the near surface. The increased subseasonal variation of the regional pollutant particulates after the SSW onset highlights the important role of the stratosphere in the regional environment and provides implications for the environmental prediction.

Thermodynamic analysis of the non-ideal cryogenic packed bed regenerator for the liquid air energy storage system

Liquid air energy storage (LAES) is one of the most recent technologies introduced for grid-scale energy storage. The cryogenic regenerator, which can greatly affect the system efficiency, is the key component of the system. A non-ideal packed bed regenerator for the LAES system was investigated. The cold energy loss and the axial heat conduction of the packed bed regenerator exist in the intermittent period between the charging and discharging process, which significantly degrades the system performance. With rock particles used as the cold energy storage medium, the axial temperature distributions of the packed bed regenerator with different initial temperatures and intermittent periods were compared. Also, the cold energy loss with different boundary conditions was analysed. The results show that the intermittent period exacerbates the negative impact of the axial heat conduction on the performance of the packed bed, and the thickness of the thermocline decreases as the inlet temperature of the cold end decreases. Moreover, as the cold energy loss increases, the cold energy storage efficiency of the packed bed decreases significantly.

LncRNA Xist Participates in Signaling Pathways Related to Pulmonary Arterial Hypertension and its Comorbidities

Population‐based studies indicate a female predominance in pulmonary arterial hypertension (PAH) of around 2 – 4 over men for all races/ethnicities and across all ages that have been studied to date. While female gender has long been established as the major clinical risk factor for PAH, other factors such as infections, autoimmune diseases, inflammation, obesity, obstructive sleep apnea and genetic predisposition have also been associated with PAH. Obstructive sleep apnea, a common comorbidity of PAH, leads to intermittent periods of apnea, significant hypoxemia, but importantly, also to hypercapnia both of which, in turn, serve to induce pulmonary arteriolar vasoconstriction and PAH. The mechanistic links between hypoxemia/hypercapnia and vascular remodeling remain unclear. Our studies sought to investigate whether obstructive sleep apnea, contributes to the severity of pulmonary artery endothelial cells (PAECs) PAH phenotype.We recently demonstrated that the increased expression and activity of the long‐noncoding (lnc)RNA‐Xist, essential for X‐chromosome inactivation and dosage compensation of X‐linked genes, drives the imbalance sex/ratio of idiopathic PAH. Using human male and female PAECs of non‐disease controls and PAH patients, in conjunction with molecular cell biology/ biochemistry, and functional approaches, we have found that the PAECs of a female specimen with PAH and obstructive sleep‐apnea displayed the highest increase in Xist expression and proliferation rate. The augmented Xist expression leads to increased expression of the X‐linked gene Elk1, a regulator of cell cycle progression in a tissue‐ and cell‐specific manner, and repression of Klf2, a key transcription factor for endothelial homeostasis and quiescence. These molecular events, more prominent in PAECs of female with PAH and comorbid obstructive sleep apnea, may account for their hyper‐proliferative phenotype. Klf2 also targets several endothelial signature genes that regulate blood pressure, angiogenesis, vascularization etc. Our studies suggest that lncRNA Xist and its signaling network participate in various pathways related to PAH and its comorbidities.

Chemostratigraphic characteristics of trace elements, biomarkers and clay mineralogy indicating environmental conditions within Aptian sediments of the Organyà Basin, North‐east Spain, prior to the onset of OAE 1a

AbstractShifting palaeoceanographic and palaeoclimatic conditions together with fluctuating eustatic sea levels during the Early Cretaceous Aptian stage led to a globally widespread deposition of organic‐rich marine sediments designated Oceanic Anoxic Event 1a. Here a detailed lithostratigraphic and geochemical study is presented for 35.6 m of the Cabó Formation, part of the Organyà Basin, North‐east Spain, to assess intermittent periods of enhanced organic carbon preservation in Lower Aptian sediments preceding Oceanic Anoxic Event 1a. The Organyà area contains well‐exposed outcrops of Mesozoic black to dark grey marlstones and limestones with variable amount of organic matter (OM) indicative of oxygen‐deficient conditions. Previous work in a section near the town of Organyà focussed on lithostratigraphy and biostratigraphy and assigned a Barremian–Aptian age. This study aims to provide an updated age based on carbon isotope correlation established elsewhere, and assess the chemostratigraphic characteristics of the Barremian–Aptian to clarify environmental changes regarding oxygen deficient conditions in the basin at that time. The δ13Corg values fluctuate from −22.1 to −24.4‰ showing concurrence with results at the El Pui section west of the studied section. Chemostratigraphic correlation of the δ13Corg reveals that the section is within segment C2, in the Lower Aptian. Redox‐sensitive trace elements (V, Ni, Co, Cr, Cu, Mo) indicate heightened dysoxic conditions at five organic‐rich layers, here designated carbonaceous layers (TOC >2%), associated with enhanced terrigenous fluxes coincident with increased major elements (Al, Si and Ti) during these intervals. Biomarkers from six levels showed n‐alkane distributions with chain lengths from nC14 to nC34, mostly below nC21 indicating a predominance of marine‐derived OM. Climate conditions inferred from variable smectite, and kaolinite content suggests fluctuating humid‐warm conditions. The results thus reveal that the Organyà Basin experienced intervals of distinct oxygen‐poor conditions prior to the onset of Oceanic Anoxic Event 1a.

Robotic-assisted minimally invasive thymectomy for myasthenia gravis with thymoma.

Robotic-assisted minimally invasive thymectomy for myasthenia gravis with thymoma.

Wavelet analysis for cyclic combustion dynamics of a multi-cylinder CRDI diesel engine fuelled with a blending of argemone biodiesel-diesel oil.

Higher cyclic variability in combustion adversely influences emissions, efficiency, and driveability of internal combustion engines. In this paper, we used wavelet transform techniques to investigate the dynamical characteristics of a combustion process in numerous combustion parameters of a 4-cylinder turbocharged common rail direct injection (CRDI) diesel engine fuelled with Argemone mexicana biodiesel (AGB)/diesel blended fuel. In addition, statistical analysis is described to validate the results of the wavelet spectrum methods for cyclic variation in the diesel engine. The results show that the cyclic variations in IMEP and Pmax are sensitive to the engine load and fuel properties. The coefficient of variation of both combustion parameters decreases as engine load increases for all tested fuels. Moreover, adding Argemone mexicana biodiesel (AGB) into diesel fuel up to 20% (AB20) reduces cyclic variations in combustion parameters at all tested engine loads. Furthermore, the global wavelet spectrum and wavelet power spectrum are utilized to identify the dominant oscillatory combustion modes. The cycle-to-cycle fluctuations in combustion parameters (i.e., IMEP and Pmax) exhibit multi-scale dynamics for all experimental conditions. Compared to long and intermediate oscillations in diesel fuel, AB10 and AB20 fuel showed short and intermittent period fluctuations. The findings of this experimental work will be helpful to optimize engine control strategies for AGB/diesel blended fueled multi-cylinder CRDI diesel engines.

Summer Lake Destratification Phenomenon: A Peculiar Deep Lake on the Tibetan Plateau

Lake water temperature and the related thermal structure influence not only the provision of ecosystem services in lacustrine environments but also the interactions with regional climate. However, continuous lake temperature monitoring across the Tibetan Plateau is sparse, limiting our understanding of lake thermal and mixing dynamics and hindering the verification of modeling results in this region. Based on in-situ water temperature and meteorological observations, this study revealed a special summer destratification phenomenon of a deep alpine lake, Langa Co. The results indicate that Langa Co is a discontinuous cold polymictic lake, which becomes completely mixed and reaches a homogeneous water temperature frequently during spring and autumn. Further, the intermittent periods of stratification in summer only last a few days, which is rare for such a deep lake. As an example of a discontinuous cold polymictic lake that contrasts with the typical dimictic pattern of alpine lakes, studies of Langa Co help to gain insights into lake thermal processes and thermoregulation mechanisms and establish a reference for lake model evaluation and parameterization on the Tibetan Plateau.

The clinical application of mobile internet remote guidance platform for vestibular rehabilitation

Objective: To guide the patients with vertigo who are suitable for vestibular rehabilitation therapy (VRT), and to evaluate the curative effect through a remote guidance platform based on mobile internet. Methods: Adult outpatients, who were diagnosed as vestibular disorders and required VRT, were selected and conducted baseline evaluation and formulated vestibular rehabilitation plan according to their symptoms, diagnosis and vestibular function examination results. These patients downloaded and installed the mobile internet remote guidance platform app for VRT, and then registered and uploaded medical records. According to the VRT plan formulated by clinicians for patients, the platform launched corresponding exercise guidance videos to guide them to complete 4-week VRT exercise at home. Before and after VRT, the patients were scored with Visual Analogue Scale (VAS), Activities-specific Balance Confidence (ABC), Dizziness Handicap Inventory (DHI) and Self-rating Anxiety Scale (SAS). The rehabilitation effects were statistically analyzed by SigmaStat 4.0 software. Results: From October 2019 to October 2021, 233 patients with vertigo completed the registration of vestibular rehabilitation guidance platform, of whom 187 patients insisted on 4-week rehabilitation training and completed the scale evaluation. Among 187 patients, 65 were male and 122 were female; Age was (49.8±16.0) years; The medical history ranged from one to 192 months, with a median of eight months. Compared with that before rehabilitation exercise, the subjective feeling of vertigo in 170 patients was improved, and the overall effective rate was 90.9% (170/187). The subjective symptoms of vertigo were basically improved after rehabilitation training in patients with unilateral vestibular dysfunction, vestibular neuritis, sudden deafness with vertigo, Hunt syndrome and acoustic neuroma. There were significant differences in ABC, DHI and SAS scores before and after VRT (P<0.05). Of those patients with Meniere's disease in the intermittent period and the patients with Meniere's disease who underwent surgical treatment, more than 90% of their subjective symptoms of vertigo or dizziness improved after VRT, and there were significant differences in the scores of ABC, DHI and SAS before and after VRT exercise (P<0.05). In patients with vestibular migraine, 36.7% (11/30) had no improvement or even aggravation of subjective symptoms of vertigo after VRT, however, the DHI score after rehabilitation exercise was lower than that before exercise, and the difference was statistically significant (P<0.05). In patients with bilateral vestibular dysfunction, although most (6/8) subjective symptom scores were improved compared with those before exercise, there was no significant difference in ABC, DHI and SAS scores before and after rehabilitation (P>0.05). Conclusion: VRT with the help of vestibular rehabilitation mobile internet remote guidance platform can effectively improve the subjective symptoms of vertigo, balance ability and anxiety in patients with unilateral vestibular lesions.

An adaptive approach to quantify weather-within-climate rainfall characteristics

Knowledge of subseasonal-to-seasonal (S2S) rainfall characteristics such as onset, duration, and demise of the rainfall cycle, and characteristics of dry periods that are between rainfall seasons, can provide important insight for the agriculture, health, disaster, and energy industries. Several methods have attempted to calculate temporal characteristics of rainfall and few have worked with intermittent dry periods and calculate intermittent dry period characteristics. Issues arise when applying these methods for complex rainfall regimes, or regions that have one or more of the following: (1) multiple rainfall seasons in a given year, (2) a relatively wet dry season, (3) unclear transitions between wet and dry seasons. This study develops a new and comprehensive method for calculating S2S rainfall characteristics, especially for regions that have complex annual rainfall cycles. The method consists of three steps: (1) create the annual cycle climatology of rainfall and classify its modality by the presence or absence of intermittent dry period(s), (2) identify seasonal windows of the rainfall cycle based on its climatological modality, (3) calculate yearly intermittent dry period characteristics and calculate temporal rainfall characteristics for each year using information on daily rainfall amount and the concurrent rate of change. Application and results of the method are given for the Caribbean, which exhibits the properties of a region with complex rainfall regimes. The method can be utilized under a meteorological or agronomical lens and is able to delineate false meteorological and agronomical onsets and demises. Meteorological onsets and demises that are calculated via each year’s Early-Rainy Season (ERS) and Late-Rainy Season (LRS) mean thresholds effectively characterize the seasonal evolution of mean onsets and demises in the Caribbean. The year-to-year variability of Mid-Summer Drought (MSD) characteristics, and onsets and demises that are calculated by climatological ERS and LRS mean thresholds resemble the variability of seasonal rainfall totals in the Caribbean and are statistically significantly correlated with the identified dynamical processes that impact each seasonal component of the rainfall cycle. The method has important implications for prediction, modeling capabilities, and understanding the variability of rainfall across timescales.

Maternal Levothyroxine Treatment as an Etiologic Factor in the Development of Infantile Craniosynostosis

AbstractCraniosynostosis (CS) is a condition characterized by premature fusion of one or more calvarial sutures. Numerous studies have demonstrated a correlation between CS and maternal hypothyroidism (MH), but research into this relationship has been scarce. A six-day-old male patient presented for initial neurosurgical consultation with trigonocephaly and prominent metopic ridging. A CT scan of the head confirmed the diagnosis of metopic CS, and it was revealed during the examination that the mother suffered from hypothyroidism during her pregnancy. Two theories provide a potential etiologic basis for the development of CS in infants born to hypothyroid mothers treated with levothyroxine. It is possible that the transplacental delivery of levothyroxine results in fetal thyrotoxicosis. Alternatively, intermittent periods of maternal hypothyroxinemia may encourage fetal thyroid hyperactivity to compensate for insufficient maternal thyroid hormones. Regardless, both theories must be formally investigated in order to elucidate the true association between CS and MH.

Modelling the Effect of ‘Roller Dynamics’ on Storm Erosion: Sylt, North Sea

Coastal storm erosion can lead to episodic morphological changes and hinterland flooding that requires sustainable management. An accurate estimation of storm erosion can determine the success of hazard mitigation strategies. Two morphological models, Delft3D and XBeach, were applied separately to a stormy period with “Roller” and “No Roller” wave dynamics activated, to estimate erosion of the beach and dune system on the Sylt island. This is the first numerical impact assessment of roller dynamics on coastal erosion using the two models. The choice of model had more impact on the hydrodynamic and morphological predictions than the option to include or omit roller dynamics. Agreement between measured and simulated waves was higher in Delft3D (R2 &gt; 0.90 and RMSE &lt; 0.15 m) than XBeach. Storm erosion in both models had the highest sensitivity to the roller parameter Beta. Both models predicted a similar storm erosion pattern along the coast, albeit different magnitudes. It is found that Delft3D cannot produce comparable storm erosion to XBeach, when the roller dynamics and avalanching are considered. Delft3D is less sensitive to the roller dynamics than XBeach. Including roller dynamics in Delft3D increased storm erosion up to 31% and in XBeach decreased the erosion down to 58% in the nearshore area, while the erosion in the dune area increased up to 13% in Deflt3D and up to 97% in XBeach. Both models are skilled in simulating storm impact. For the simulation of a storm period with intermittent calm periods, it is suggested that applying a time-varying parameter setting for wave dynamics and sediment transport to capture storm erosion and post-storm beach recovery processes could improve results. Such a modelling approach may ultimately increase the accuracy of estimating storm erosion to support coastal management activities (e.g., sand nourishment volume).

Daily Time-Restricted Feeding And Alternative Day Fasting For Weight Management: Comparative Analysis

Abstract The approach of limiting nutritional intake frequency, but without a large reduction of the amount of calories consumed, the so-called intermittent fasting, has gained growing popularity. Intermittent fasting is an umbrella term for meal timing schedules that cycle between voluntary fasting (or vastly reduced calories intake) and non-fasting over a defined period. In our study, we compared two of the most popular intermittent fasting regimens — 16/8 time-restricted feeding and 5/2 alternate day fasting. A total of 16 healthy young women (under 30 years of age) participated in the study, eight in each intermittent fasting group, for six consecutive weeks. Among anthropometric parameters, height, weight, umbilical waist circumference, sagittal abdominal diameter, and skinfold thickness were measured and body mass index and relative body fat were calculated. Differences between the initial values and the values after the six-week intermittent fasting period were calculated and compared between the two groups. We found no statistically significant difference (p &gt; 0.05) between 16/8 time-restricted feeding and 5/2 alternate day fasting regimens in differences over the six-week period for the tested parameter, including weight loss. As there were no significant differences for overall changes in parameter values in the six-week period between the two intermittent fasting regimens, we concluded that both were equally suitable for weight loss programmes.

Three-dimensional numerical simulation of circulation and vertical temperature structure during summer in Cockburn Sound

Cockburn Sound is an important embayment close to a metropolitan area in Western Australia. In this paper, we study summer circulation patterns, volume balance, and mixing processes in Cockburn Sound and adjacent shelf using in-situ oceanographic surveys made during the 2016–2017 austral summer and numerical simulations using the Finite Volume Coastal Ocean Model (FVCOM). The model results revealed that the local wind variability played a primary role in regulating the water volume in the embayment, with decreasing volume associated with south-southeasterly winds. In Cockburn Sound, a diel stratification cycle during summer was caused by accumulation of heat in the surface layer due to net air–sea heat flux (mostly solar radiation) during the daytime, and wind mixing due to sea-breezes in the afternoon and convective mixing due to nightly heat losses. The regularity of well-mixed nature can be interrupted with intermittent periods of vertical stratification. During March 2017, very strong vertical stratification that coincided with low oxygen conditions was observed in the near bottom water. By analyzing the model results, we show that high air temperature, weak winds, and the southward compensating colder inflow at depth from the coastal waters to the north caused the sustained temperature difference between surface and bottom layers during March 2017. We conclude that this thermal stratification restricted ventilation of the bottom water, explaining the observed low oxygen content.Plain language SummaryLow oxygen conditions were observed in the bottom water of Cockburn Sound (a semi-enclosed coastal embayment) during the austral summer of 2017. This was unexpected in view of the shallow water depth and strong local wind conditions which should ensure that the water-column is well ventilated. However, modeled temperature profiles showed that thermal stratification lasting for up to a week can sometimes occur during late summer, potentially restricting oxygen ventilation. The stratification events are caused by a combination of high air temperature (especially when it remained high at night), low wind speed and inflow of cooler sub-surface water. Global warming is expected to enhance thermal stratification, reduce oxygen solubility and accelerate biological oxygen demand increasing the future risk of hypoxia in the area.

Performance evaluation of intermittent air supply system: a case study in Xi’an

Intermittent air jet strategy (IAJS) has been proven to provide a satisfactory indoor thermal climate with high energy efficiency in spaces with high occupancy density. Compared with traditional ventilation strategy, IAJS system creates heterogeneous conditions around the occupants, which complicates the relationship between thermal sensation and thermal comfort. The effect of different intermittent cycles on the thermal comfort of occupants needs to be further discussed. In addition, it is necessary to investigate whether IAJS system can play a better role in hot and humid summer conditions in China. Experiments were conducted in a chamber with two rows of seated occupants. Twelve cases were designed, including different combinations of room air temperatures (24°C, 26°C and 28°C) and intermittent period (start 90 s stop 90 s, start 3 min stop 1.5 min, start 1.5 min stop 3 min and start 3 min stop 3 min). Twelve subjects were recruited for subjective investigations. The subjects performed sedentary work and wore summer clothing. Subjective responses to the thermal environments were collected. Wind speed, temperature and CO2 concentration in the occupied area were measured. The results show that IAJS has a potential to be used as a primary ventilation system primary ventilation system such as classrooms in China. When the indoor air was set between 24°C and 26°C, IAJS could create a thermal climate that made the occupants thermally neutral. Additionally, IAJS created an indoor thermal environment acceptable to most occupants, even at a setting temperature of 28 °C.

Late Pliocene continental climate and vegetation variability in the Arctic-Atlantic gateway region prior to the intensification of Northern Hemisphere glaciations

We describe Pliocene palynological assemblages from ODP Hole 910C on the Yermak Plateau, Arctic Ocean. Analysis of high-resolution (~10 ± 3 ka) sampling allows us to detect changes in late Pliocene vegetation biomes corresponding to climatic variability between ~3.4 to 2.6 Ma. Findings show that a cool temperate and mixed boreal forest ( Pinus-Tsuga-Picea-Alnus-Ulmus community) initially dominated the Arctic-Atlantic gateway region. Following the onset of Marine Isotope Stage M2 cooling, ~3.3 Ma, there was a marked decline in vegetation coverage (low abundance of Pinus, Abies community). The mid Pliocene warm period that followed at ~3.2 to 3.0 Ma showed an increase in percentage of thermophilic and moist boreal taxa ( Tsuga-Thuja- Cupressaceae -Betula-Ilex community) suggesting influx of warm Atlantic Current. The dominance of Pinus-Ulmus persisted until ~3.0 Ma. Intermittent cooler and warmer periods occurred after 2.9 Ma, with an increase in herbaceous pollen and cryptogamic spores. This was followed by an abrupt change at ~2.73–2.64 Ma marked by a prominent shift from taiga to tundra-steppe vegetation, and coinciding with the intensification of Northern Hemisphere Glaciation ~2.65 Ma. Occurrences of Impatiens pollen indicates frost-free conditions in the region until ~2.7 Ma. Our high resolution analysis of palynological assemblages synchronizes closely with the Marine Isotope record, in general; however, we show that the mid Pliocene warm period was interrupted by short spells of intermittent cooler periods. • Palynological succession ~3.40 to 2.62 Ma indicate biome change in ODP Hole 910C, Yermak Plateau. • Mixed boreal forest dominated until Marine Isotope Stage (MIS) M2 (~3.30 Ma ago). • During 3.21 to 3.02 Ma pollen taxa indicate warmer period obstructed by two cooling phases. • A shift from Taiga to Tundra-steppe vegetation was recorded between ~2.73–2.64 Ma and Impatiens pollen shows frost-free climate. • The intensification before Northern Hemisphere Glaciation was characterised by intermittent short-term interstadials.

The Lewis Growth Rule for Developing Economies

For developing economies, adequate rates of capital formation are required for sustained economic growth, and policy makers have to consider the ratio of savings to invest in capital formation while still being supportive of other economic needs (e.g., servicing of current loans and payment of salaries and administrative overheads). We evaluated the expenditure-savings nexus of four emerging economies (i.e., Ghana, Botswana, Barbados, and Trinidad and Tobago) to investigate, in accordance with the seminal research of Sir Arthur Lewis, how the growth rates of savings and expenditure impact the accumulation of capital and, thus, spur economic development. Based on Lewis' research, we developed the Lewis Growth Rule (LGR) for developing economies – that is, emerging economies can best sustain economic development by maintaining a growth in savings that exceeds that of expenditure and by investing the surplus in the accumulation of capital. As a takeoff strategy for economic development, emerging economies' expenditure should grow by 5%–7%, whereas savings should grow by 7%–12%. We assessed the performance of the LGR by examining the two African and two Caribbean economies using data from the Penn World Tables. Our examination results of long-term trends in these economies demonstrate intermittent periods where the surplus gap as required by the LGR is observed with a downward trend for Barbados and Ghana, while upward for Botswana and Trinidad and Tobago. The impact of Ghana's significant continuous savings gaps on per capita GDP growth is significant over the analysis period. Barbados demonstrated a much lower marginal savings gap, but its positive impact on per capita GDP growth was much higher than that of Ghana. The findings have important implications for policy makers. While a savings gap is important for developing economies, political conflicts depress its impact on the real economy. Hence, the most important is the suggestion that, although critical to capital accumulation, the size of a positive savings gap does not have to be as large as Lewis' rule suggests for economic growth to be sustained. Coordinated government policies, growth supportive institutional arrangements, and investments in technology are also critical in unlocking high productivity that boosts and sustains real economic growth.

Comparative population genomics reveals glacial cycles to drive diversifications in tropical montane birds (Aves, Timaliidae)

Many bird species are specialized to live in the broadleaved, evergreen forests in the mountain regions in Southeast Asia. These mountain habitats are not continuously distributed as the different mountain areas are separated by lowlands, which has restricted gene flow and thus contributed to the high biological diversity in this region. The degree of connectivity between mountain areas has fluctuated with the Pleistocene glacial cycles, being largest during the glaciations when the mountain forests spread to lower elevations. Here we study how the intermittent periods of restricted gene flow and connectivity between the populations of five montane species of babblers (Aves, Timaliidae) in Vietnam may be traced in their genomes. The results suggest that the babbler species in the Central Highlands have been isolated from their sister-populations in northern Vietnam for between ca. 585 and 380 ky. For two species with populations in both the Central Highlands and the Da Lat region, we found that these split at more or less the same time (440–340 kya). We also found a significant statistical correlation between the time of the splits of these populations and the lowest altitude at which they are known to occur (no similar correlation was found with the geographic distances between populations). The populations in northern Vietnam show higher genetic variation than their counterparts in South-Central Vietnam, supporting the postulate that smaller populations may have lower genetic variation than larger. In accordance with this, we found the lowest genetic variation in the two species with the smallest populations in the Central Highlands. These two populations also show low levels of genomic heterozygosity. Our results show that the south-central populations of the studied babbler species are genetically distinct from their sister-populations in northern Vietnam, providing additional argument for the long-term protection of the evergreen mountain forests in Southeast Asia.

Customer complaints encountered in the online food retail during the COVID-19 intermittent curfew period

Almost everything has changed fundamentally with the coronavirus (COVID-19) epidemic. The pandemic has adversely affected the retail industry and the global economy. After detecting COVID-19, customers’ shopping preferences have moved to popular platforms like online shopping websites. Meanwhile, due to inadequate distribution structures and decentralized supply chain networks of businesses, customers have experienced many failures in service encounters. This study employed a document review method to analyse customer complaints covering common logistic service failures in the food sector during the three months (March, April and May 2020) intermittent curfew period. In addition, using content analysis, “şikayetvar.com” complaints were classified according to the service quality gap model. Since disruptions in the food industry are critical with their stimulating effects on supply chains, this industry has been analysed in detail. In terms of practical contribution, the study introduces an insight to enhance the customer service capabilities of private shopping sites. Furthermore, the theoretical background of the study reveals the service quality dimensions prioritized by customers in the pandemic environment and their critical role in service quality gaps.

Clogging and Water Quality Change Effects of Typical Metal Pollutants under Intermittent Managed Aquifer Recharge Using Urban Stormwater.

Managed aquifer recharge (MAR) using urban stormwater facilitates relieving water supply pressure, restoring the ecological environment, and developing sustainable water resources. However, compared to conventional water sources, such as river water and lake water, MAR using urban stormwater is a typically intermittent recharge mode. In order to study the clogging and water quality change effects of Fe, Zn, and Pb, the typical mental pollutants in urban stormwater, a series of intermittent MAR column experiments were performed. The results show that the type of pollutant, the particle size of the medium and the intermittent recharge mode have significant impacts on the pollutant retention and release, which has led to different clogging and water quality change effects. The metals that are easily retained in porous media have greater potential for clogging and less potential for groundwater pollution. The fine medium easily becomes clogged, but it is beneficial in preventing groundwater contamination. There is a higher risk of groundwater contamination for a shallow buried aquifer under intermittent MAR than continuous MAR, mainly because of the de-clogging effect of porous media during the intermittent period.