Comprehensive analysis of glacier recession(2000-2020)in the Nun-Kun Group of Glaciers,Northwestern Himalaya

Himalayan glaciers are shrinking rapidly,especially after 2000.Glacier shrinkage,however,shows a differential pattern in space and time,emphasizing the need to monitor and assess glacier changes at a larger scale.In this study,changes of 48 glaciers situated around the twin peaks of the Nun and Kun mountains in the northwestern Himalaya,hereafter referred to as Nun-Kun Group of Glaciers(NKGG),were investigated using Landsat satellite data during 2000-2020.Changes in glacier area,snout position,Equilibrium Line Altitude(ELA),surface thickness and glacier velocity were assessed using remote sensing data supplemented by field observations.The study revealed that the NKGG glaciers have experienced a recession of 4.5%±3.4%and their snouts have retreated at the rate of 6.4±1.6 m·a^(-1).Additionally,there was a 41%increase observed in the debris cover area during the observation period.Using the geodetic approach,an average glacier elevation change of-1.4±0.4 m·a^(-1)was observed between 2000 and 2012.The observed mass loss of the NKGG has resulted in the deceleration of glacier velocity from 27.0±3.7 m·a^(-1)in 2000 to 21.2±2.2 m·a^(-1)in 2020.The ELA has shifted upwards by 83.0±22 m during the period.Glacier morphological and topographic factors showed a strong influence on glacier recession.Furthermore,a higher recession of 12.9%±3.2%was observed in small glaciers,compared to 2.7%±3.1%in larger glaciers.The debris-covered glaciers showed lower shrinkage(2.8%±1.1%)compared to the clean glaciers(9.3%±5%).The glacier depletion recorded in the NKGG during the last two decades,if continued,would severely diminish glacial volume and capacity to store water,thus jeopardizing the sustainability of water resources in the basin.

The impact of earlier flood recession on metacommunity diversity of wintering waterbirds at shallow lakes in the middle and lower Yangtze River floodplain

The hydrological regime in wetlands plays an important role in the process of wintering waterbird metacommunity assemblage.However,increasing frequency of extreme climate and the intensification of human activities,such as the construction of sluices and dams,have resulted in frequently abnormal hydrological regime in the middle and lower Yangtze River floodplain.In recent years,earlier flood recession has become one of the main hydrological problems faced in the shallow lakes,having a great impact on wetland biodiversity.It is necessary to understand the impact of earlier flood recession on waterbirds,an indicator of wetland biodiversity,and the metacommunity concept is helpful to elucidate the underlying mechanism involved in the processes of assemblage by waterbird communities.In this study,we surveyed the wintering waterbirds at three sub-lakes of Caizi Lakes during 2019-2020 and 2020-2021 and compared the richness,abundance,alpha and beta diversity of waterbirds in and among local metacommunities under earlier flood recession and normal hydrological regime.The results showed that the earlier flood recession reduced the species richness in the early stage and abundance in the late stage,it also reduced the Shannon-Wiener index in the early stage and increased the dissimilarity between and within waterbird metacommunities in the late stage.The partition of beta diversity showed that the turnover component played a major role in the process of waterbird metacommunity assemblage.It was found that the earlier flood recession reduced the richness,abundance in different stages of flood recession,which also increased the turnover of waterbirds.Metacommunities with high habitat heterogeneity had better resistance to abnormal hydrological regime,which resulted in high dissimilarity between and within metacommunities.The results of this study provide important information for waterbird conservation and water level management at shallow lakes in the middle and lower Yangtze River floodplain.

Comparison of conventional and Hang-back methods of inferior oblique recession in V-pattern strabismus with inferior oblique overaction

AIM:To compare outcomes of conventional and Hangback methods of inferior oblique(IO)recession in V-pattern strabismus with inferior oblique overaction(IOOA).METHODS:Comparative randomized study was conducted consisting of 50 patients,age 6 to 35 y having V-pattern strabismus[>15 prism diopter(PD)]with IOOA.They were divided equally in two groups and underwent IO recession,group A by conventional method and group B by Hang-back method.Parameters evaluated were reduction in V-pattern and IOOA,shift in torsion,improvement in binocular status.Success was a residual V-pattern of less than 10 PD at 1 y of follow up.RESULTS:The mean V-pattern preoperatively and postoperatively at 1 y was 24±5.4 PD and 4.2±3.51 PD in group A and 23.44±6.44 PD and 5.76±3.8 PD in group B respectively.The mean reduction in V-pattern was 20±6.78 PD in group A and 18.2±5.48 PD in group B.The mean correction of IOOA was 18.48±3.13 PD in group A and 16±2.93 PD in group B.Mean shift in extorsion was 3.08±1.8 degree in group A and 3.72±2.14 degree in group B.CONCLUSION:Both the procedures achieve a significant and comparable reduction in V-pattern and IOOA.Hang-back recession being a landmark free surgery eliminates the need for intrascleral suturing thereby reducing the risk of scleral perforation with possible postoperative adjustment of muscle.It may be considered as a good alternative for IO recession in patients of V-pattern strabismus with mild to moderate amount of IOOA.

A Two-parameter Exponential Recession Model for Simulating Cropland Soil Moisture Dynamics

To simulate the soil moisture variation in cropland, a two-parameter exponential recession model was derived to depict the recession process of soil moisture in the root zone. The model is based on the assumption that the recession rate of soil water is proportional to the potential evapotranspiration rate and the difference of soil water content and steady soil water content. Two parameters in this model are soil texture-dependent recession constant and steady soil water content. The model was calibrated and validated with measured soil water data at two experiment sites in North China with different soil textures and cropping systems. Coefficients of determination between measured and model simulated soil water content were all greater than 0.7, indicating that both models gave satisfactory simulation results. Results showed that values of two parameters mentioned above are both larger for finer soil than those for coarser soil. At the same potential evapotranspiration rate and soil water content, the recession rate of finer soil is usually lower than that of coarser soil. The proposed model can be used in irrigation management to predict approximate date for irrigation, as well as be embedded into watershed hydrological models to estimate the antecedent precipitation index.

Anterior lamellar recession for management of upper eyelid cicatricial entropion and associated eyelid abnormalities

AIM：To evaluate the functional and aesthetic outcomes of upper eyelid cicatricial entropion（UCE） correction using anterior lamellar recession（ALR） with addressing the associated conditions including dermatochalasis,brow ptosis,blepharoptosis,and lid retraction.METHODS：Chart review of patients with upper lid cicatricial entropion who had undergone ALR from 2013 to 2016 was reviewed.Success was defi ned as the lack of any lash in contact with the globe,no need for a second procedure,and acceptable cosmesis at the fi nal follow up.RESULTS：Sixty eight patients（97 eyelids） were operated by ALR with simultaneous correction of associated lid problems in each case when necessary.The mean followup time was 17.8 mo（range,6.0-24.0 mo）.Concomitantly,levator tucking was performed in 19 eyelids（19.6%）,upper lid retractor recession in 18 eyelids（18.6%）,and internal browpexy in 31 eyelids（32.0%）.In 95.8% of patients（95%CI：0.85-0.96）,satisfactory functional and cosmetic outcome was achieved with a single surgical procedure.CONCLUSION：Based on the principles of lamellar recession and concurrently addressing the associated lid problems,this approach is an effective and safe treatment of UCE.

Estimation of groundwater residence time and recession rate in watershed of the Loess Plateau

Groundwater residence time is an important indicator of hydrological cycle and essential for water resources development and utilization. In this paper, groundwater residence time in non-flood season, flood season and water year has been determined from daily streamflow hydrograph of ten hydrological stations in Wudinghe River Basin located in the middle reaches of the Yellow River Basin. Results have showed that： baseflow recession constant in Wudinghe River Basin ranges from 0.72 to 0.94 with a larger recession rate in flood season than that in non-flood season. Spatially, the recession rate of baseflow in loess area is the biggest, but is the smallest in the sandy area. The half-residence time of groundwater varies from 1.8 to 45.5 days while overall residence time of groundwater is between 34 and 342 days in different sub-basins of the Wudinghe River Basin. The annual average overall residence time of groundwater decreases from 117 days in the upper reaches to 73 days in the lower reaches.

Systematic review of suicide in economic recession

AIM: To provide a systematic update of the evidence concerning the relationship between economic recession and suicide.METHODS: A keyword search of Ovid Medline, Embase, Embase Classic, PsycI NFO and PsycA RTICLES was performed to identify studies that had investigated the association between economic recession and suicide. RESULTS: Thirty-eight studies met predetermined selection criteria and 31 of them found a positive association between economic recession and increased suicide rates. Two studies reported a negative association, two articles failed to find such an association, and three studies were inconclusive. CONCLUSION: Economic recession periods appear to increase overall suicide rates, although further research is warranted in this area, particularly in low income countries.

Gingival unit transfer using in the Miller Ⅲ recession defect treatment

The most significant factor for the success in soft tissue grafts is the synergistic relation between vascular configuration and involved tissues. In the soft tissue graft procedures, site specific donor tissue is assumed to have improved potential for function and aesthetic survive at recipient sites. On a clinical level, using site specific gingival unit graft that placed on traditionally prepared recipient site, results in predictable root coverage. In this case report the clinical effectiveness of gingival unit transfer(GUT) technique performed on Miller Ⅲ recession was presented and a similar recession case treated with free gingival graft(FGG) technique for comparison. Probing depth, recession depth, keratinized tissue width and clinical attachment level clinical parameters were measured at baseline and postoperative 8 mo. Percentage of defect coverage was evaluated at postoperative 8 mo. Creeping attachment was assessed at postoperative 1, 3, 6 and 8 mo. The GUT revealed better defect coverage and creeping attachment results than the FGG in the treatment of Miller Ⅲ defects.

Relation between early postoperative deviation and long-term outcome after unilateral lateral rectus recession and medial rectus resection for adult exotropia

AIM： To evaluate the relationship between early postoperative deviation and long-term outcome after unilateral recession and resection surgery for adult exotropia, and to evaluate exotropic shift after surgery.METHODS： This was a retroprospective study involving adult patients with exotropia who underwent unilateral recession and resection surgery and were followed up for at least 2 y. The results were evaluated at 2 y and the final visit. Factors influencing a successful outcome were analyzed. Early postoperative deviation at 1 wk was used to evaluate relationship with long-term outcome. The longterm outcome was classified into 3 groups： successful, acceptable, and poor. Successful outcome was defined as a distance deviation between esodeviation 8 prism diopters（PD） and exodeviation 10 PD.RESULTS： Forty-two patients were enrolled. The mean age at surgery was 26 y（range, 15-49 y）. The median follow-up period was 30 mo（range, 24-108 mo）. Successful outcome was found in 81% of patients at 2 y and in 71% at the final visit. Overcorrection at 1 wk postoperatively was associated with a successful outcome at 2 y. Initial postoperative alignment between orthotropia and esodeviation of 8 PD had the highest chance of a successful outcome（RR=2.2）. The mean postoperative exotropic drift was 4.7 PD at the first month and 9.3 PD at 2 y.CONCLUSION： Initial postoperative deviation can predict long-term outcome after unilateral recession and resection surgery for adult exotropia. The most desirable outcome at 1 wk post-operatively was orthotropia to small esodeviation. Most patients have exotropic drift at a subsequent follow-up, especially in the first month after surgery.

Comparison of excyclotorsion following graded inferior oblique recession for primary versus secondary inferior oblique overaction

AIM:To compare the changes in excyclotorsion after inferior oblique(IO)recession in patients with primary and secondary inferior oblique overaction(IOOA).METHODS:We retrospectively analyzed the data obtained from patients with IOOA who underwent graded IO recession.The patients were followed up for at least 3 mo after surgery.Fundus photographs were taken preand postoperatively,and the sum of the angles of torsion in both eyes was used to analyze changes in excyclotorsion.Patients were divided into two groups:those diagnosed with primary IOOA were enrolled in the 1’IOOA group,and those diagnosed with secondary IOOA caused by superior oblique palsy(SOP)were enrolled in the 2’IOOA group.Excyclotorsion before and after surgery were compared between the two groups.RESULTS:A total of 78 patients were enrolled in this study:34 eyes in the 1’IOOA group and 44 eyes in the 2’IOOA group.In the 78 patients,torsional angle significantly decreased from 15.31°±7.40°to 12.11°±6.53°after IO recession(P<0.001).Mean preoperative torsional angle was larger in the 2’IOOA group than in the 1’IOOA group(P=0.03).In both groups,excyclotorsion significantly decreased after IO recession(P=0.001 and P<0.001,respectively);however,there was no significant difference in the amounts of changes in excyclotorsion between the two groups.CONCLUSION:Excyclotorsion is significantly larger in secondary IOOA than in primary IOOA,and a significant decrease in the torsional angle occurs after IO recession in both types of IOOA.

Lateral rectus muscle recession and the vertical palpebral fissure height: to do or not to do inter-muscular septum dissection?

In this study, we aimed to evaluate changes of vertical palpebral fissure height （VPFH） after unilateral lateral rectus muscle recession. Twenty-five and twenty-six patients who were candidates for lateral rectus muscle recession were assigned into “with” and “without” intermuscular septum dissection study arms. The VPFH was measured at one-day before surgery and in two weeks and three months, postoperatively. Three months after surgery, significant increase of VPFH was observed in both groups （Paired t-test; P=0.005）. Also, less widening of VPFH was observed in “with intermuscular septum dissection” group （Change in VPFH in “with intermuscular septum dissection” vs “without intermuscular septum dissection” groups： 0.48 mm vs 1.34 mm; ANCOVA test; P〈0.001）. However, such results were not observed two weeks post-operatively （Change in VPFH in “with intermuscular septum dissection” vs “without intermuscular septum dissection” groups： -0.28 mm vs 0.28 mm; ANCOVA test; P=0.302）. Intermuscular septum dissection is recommended in lateral rectus muscle recession to partially prevent the undesirable increment of VPFH.

SUB-NANOMETER POLISHING OF MAGNETIC RIGID DISK HEADS TO AVOID POLE TIP RECESSION

For the purpose of solving the problem that too large pole tip recession （PTR） is produced in magnetic rigid disk heads by mechanical polishing, a chemical mechanical nano-grinding experiment is performed by using a float-piece polisher with a tin plate to achieve a more plane and smoother surface. A basal solution, addition agents and a range of pH value are suitably selected to find a kind of slurry, with which the PTR can be controlled on sub-nanometer scale and the giant magnetic resistance （GMR） corrosion and electrostatic damage （ESD） can be avoided. Moreover, the cause that TiC protrudes from the substrate surface of the heads is studied. The appropriate shape and size of diamond abrasive are selected according to the chemical activation of A1203 and TiC in the same slurry. In this way, the chemical and mechanical interactions are optimized and the optimal surface that has small PTR and TiC asperity is achieved. Ultimatily, the chemical mechanical nano-grinding in combination with mechanical nano-grinding is adopted. Sub-nanometer PTR is achieved and the TiC asperity is eliminated by the chemical mechanical nano-grinding with large size ofmonocrystalline followed by mechanical nano-grinding with smalle polycrystalline diamonds.

A composite fall-slippage model for cliff recession in the sedimentary coastal cliffs

A composite fall-slippage model is proposed in this study for the Tertiary sedimentary coastal cliffs of Varkala in the western coastal tract of Peninsular India which are retreating landwards due to the combination of several factors.The fall model in the present study accounts both spring seepage and wave action,resulting in undercutting and this fall affects only the topmost laterite and the just below sandstone in the cliff.Slippage in this area affects all the litho-units and hence the geologic characteristics of all the litho-units are considered for developing the slippage model.This mathematically derived model can be used in other cliffs exhibiting the same morphology as well as the one controlled by the same influencing factors.This model differs from other models in incorporating multi-lithounits as well as multi-notches.Varkala cliffs form a part of the aspiring geopark in the Global Geopark Network and hence a study on the cliff recession is a pressing requirement.

Prediction of Seaward Slope Recession in Berm Breakwaters Using M5＇ Machine Learning Approach

In the design process of berm breakwaters, their front slope recession has an inevitable rule in large number of model tests, and this parameter being studied. This research draws its data from Moghim＇s and Shekari＇s experiment results. These experiments consist of two different 2D model tests in two wave flumes, in which the berm recession to different sea state and structural parameters have been studied. Irregular waves with a JONSWAP spectrum were used in both test series. A total of 412 test results were used to cover the impact of sea state conditions such as wave height, wave period, storm duration and water depth at the toe of the structure, and structural parameters such as berm elevation from still water level, berm width and stone diameter on berm recession parameters. In this paper, a new set of equations for berm recession is derived using the M5＇ model tree as a machine learning approach. A comparison is made between the estimations by the new formula and the formulae recently given by other researchers to show the preference of new M5＇ approach.

Implications of Design, Management and Recession Phase in Drip Irrigation on the Total Distribution Efficiency in Blueberry (Vaccinium corymbosum L.) Crops in Areas with High Slopes in Concordia, Argentina

The increase of human population generates the need to improve the efficiency of food production. A thorough planning is required following the scope of economic and sustainable development, being irrigation a basic tool, however water availability is restricted and it obliges farmers to progress increasing water productivity. Irrigation uses around 70% of total available fresh water, while irrigation water application efficiency is around 40%. Irrigation systems must follow strong criteria at the design stage to achieve high values of water productivity. Maintenance is indispensable to follow the original functioning level of those systems. At last the daily precise management of systems, following soil water potential, considering the effective rain storage at root depth of the crop and the evolution of daily evapotranspiration, preserving natural resources, are relevant to achieve low values of water footprint of this crop. In an 8 year drip irrigation system, the Uniformity Coefficient of Christiansen (UCC) measured was 95.14%;the Uniform Coefficient of the Minor Quart (UCMQ) was 93.16%. The Total Distribution Efficiency (EDT) was 95.13% when measurements finished while the irrigation systems is of. When measurements also considered the volume collected during the “recession phase in drip irrigation” and the “volume of water collected during recession phase in drip irrigation” collected at different points, EDT was 95.13%. Moreover it can be seen that when three different typical soil of the area were considered, the EDT was, 91.85%, 91.47% and 90.30% respectively, according with different water storage capacity of each soil. The Total Distribution Efficient is a strong method, to evaluate the design and management of drip irrigation systems, under different design criteria, management practices and maintenance of the systems. Water footprint in a blueberry (Vaccinium corymbosum L.) crop with drip and sprinkler anti-frost system, were measure and values obtained were 846, 310, 223, 212, 172 and 218 liters per kg of fresh fruit in the period 2010-2015. The UCC and the UCMQ reflects properly the irrigation design, while the EDT reflects irrigation design, management and maintenance. Water footprint is at last the strong tool to evaluate design and operation of the irrigation system and crop management.

Comparative evaluation of effect of injectable platelet-rich fibrin with collagen membrane compared with collagen membrane alone for gingival recession coverage

BACKGROUND Collagen membrane and platelet-rich fibrin(PRF)have emerged as vital biomaterials in the field of periodontal regeneration.Minimally invasive techniques are being preferred by most periodontists,as it is patient compliant with fewer post-surgical complications as compared to conventional surgical techniques.Thus,in this study we have evaluated the effect of injectable PRF(i-PRF)with collagen membrane compared with collagen membrane alone using vestibular incision subperiosteal tunnel access(VISTA)technique for gingival recession coverage.AIM To compare the efficacy of VISTA using collagen membrane with collagen membrane soaked in injectable PRF for gingival recession coverage.METHODS A split mouth randomized controlled clinical trial was designed;13 subjects having at least 2 teeth indicated for recession coverage were enrolled in this study.The sites were randomly assigned to control group(VISTA using collagen membrane alone)and the test group(VISTA using collagen membrane with i-PRF).The clinical parameters assessed were pocket depth,recession depth(RD),recession width(RW),relative attachment level,keratinised tissue width(KTW),keratinised tissue thickness(KTT),and percentage root coverage.RESULTS RD showed a statistically significant difference between the test group at 3 mo(0.5±0.513)and 6 mo(0.9±0.641)and the control group at 3 mo(0.95±0.51)and 6 mo(1.5±0.571),with P values of 0.008 and 0.04,respectively.RW also showed a statistically significant difference between the test group at 3 mo(1±1.026)and 6 mo(1.65±1.04)and the control group at 3 mo(1.85±0.875)and 6 mo(2.25±0.759),with P values of 0.008 and 0.001,respectively.Results for KTW showed statistically significant results between the test group at 1 mo(2.85±0.489),3 mo(3.5±0.513),and 6 mo(3.4±0.598)and the control group at 1 mo(2.45±0.605),3 mo(2.9±0.447),and 6 mo(2.75±0.444),with P values of 0.04,0.004,and 0.003,respectively.Results for KTT also showed statistically significant results between test group at 1 mo(2.69±0.233),3 mo(2.53±0.212),and 6 mo(2.46±0.252)and the control group at 1 mo(2.12±0.193),3 mo(2.02±0.18),and 6 mo(1.91±0.166),with P values of 0.001,0.001,and 0.001,respectively.The test group showed 91.6%,81.6%,and 67%root coverage at 1 mo,3 mo,and 6 mo,while the control group showed 82.3%,66.4%,and 53.95%of root coverage at 1 mo,3 mo,and 6 mo,respectively.CONCLUSION The use of minimally invasive VISTA technique along with collagen membrane and injectable form of platelet-rich fibrin can be successfully used as a treatment method for multiple or isolated gingival recessions of Miller’s class-I and class-II defects.

A STUDY ON RECESSION MECHANISM AND REJUVENATION WAYS OF THENORTHEAST OLD INDUSTRIAL BASE

Using the theory of regional superiority of forming and developing Of the old industrial bases and theory of transfondng industrial structure, the paper analyses the recession characteristics, reasons and mechanism of the northest Old industrial base. On the basis of analysing and using the successful experience of other countries, the authors put forward the pattern, goal and way of transforming the northeast old industrial base, combined with the particular national conditions. The poper wants to make the theory and practice system of forming and developing of the world industrial bases more perfect, and provide some experience to promote the systematic development and speed up the industrialized course in the industrial ha of developing countries.

Surgical results of the slipped medial rectus muscle after hang back recession surgery

AIM: To analyze the surgical results of a slipped medial rectus muscle(MRM) after hang back recession surgery for esotropia.METHODS: Twenty-one patients who underwent reexploration for diagnosed slipped muscle after hang back recession surgery were included in this retrospective study. Dynamic magnetic resonance imaging was performed to identify the location of the slipped muscle.Ocular motility was evaluated with assessment with prism and cover test in gaze at cardinal positions. The operations were performed by the same consultant.Intraoperative forced duction test was performed under general anesthesia. The empty sheath of the slipped MRM was resected and the muscle was advanced to the original insertion site in all patients.RESULTS: The average age of 21 patients who had consecutive exotropia with a slipped MRM at the time of presentation was 17.4±5.4y(5-50y). The average duration between the first operation and the diagnosis of the slipped muscle was 25mo(12 to 36mo). The mean follow up after the corrective surgery was 28 mo. The mean preoperative adduction limitation in the field of action of the slipped muscle was-2.26(ranging from-1 to-4). All patients had full adduction postoperatively.CONCLUSION: The diagnosis of the slipped muscle should be confirmed during the strabismus surgery. The slipped muscle may be caused due to insufficient suture and excessive rubbing of the eye. When divergent strabismus is observed after the recession of the MRM, a slipped muscle should be considered in the differential diagnosis.

Comparison of semilunar coronally repositioned flap with gingival massaging using an Ayurvedic product(irimedadi taila) in the treatment of class-Ⅰ gingival recession: A clinical study

AIM: To study the comparison in terms of root coverage the effect of gingival massaging using an ayurvedic product and semilunar coronally repositioned flap(SCRF) to assess the treatment outcomes in the management of Miller's class Ⅰ gingival recessions over a-6mo period. METHODS: The present study comprised of total of 90 sites of Miller's class-Ⅰ gingival recessions in the maxillary anteriors, the sites were divided into three groups each comprising 30 sites, Group Ⅰ-were treated by massaging using a Placebo(Ghee) Group Ⅱ-were treated by massaging using an ayurvedic product(irimedadi taila). Group Ⅲ-were treated by SCRF. Clinical parameters assessed included recession height, recession width, probing pocket depth, width of attached gingiva, clinical attachment level and thickness of keratinized tissue. Clinical recordings were performed at baseline and 6 mo later. The results were analyzed to determine improvements in the clinical parameters. The comparison was done using Wilcoxon signed rank test. The overall differences in the clinical improvements between the three groups was done using Kruskal-Wallis test. The probability value(P-value) of less than 0.01 was considered as statistically significant.RESULTS: Non-surgical periodontal therapy and gingival massaging improves facial gingival recessions and prevents further progression of mucogingival defects. Root coverage was achieved in both the experimental groups. The SCRF group proved to be superior in terms of all the clinical parameters.CONCLUSION: Root coverage is significantly better with semilunar coronally repositioned flap compared with the gingival massaging technique in the treatment of shallow maxillary Miller class Ⅰ gingival recession defects.

Impact of COVID-19 on G20 countries:analysis of economic recession using data mining approaches

The G20 countries are the locomotives of economic growth,representing 64%of the global population and including 4.7 billion inhabitants.As a monetary and market value index,real gross domestic product(GDP)is affected by several factors and reflects the economic development of countries.This study aimed to reveal the hidden economic patterns of G20 countries,study the complexity of related economic factors,and analyze the economic reactions taken by policymakers during the coronavirus disease of 2019(COVID-19)pandemic recession(2019–2020).In this respect,this study employed data-mining techniques of nonparametric classification tree and hierarchical clustering approaches to consider factors such as GDP/capita,industrial production,government spending,COVID-19 cases/population,patient recovery,COVID-19 death cases,number of hospital beds/1000 people,and percentage of the vaccinated population to identify clusters for G20 countries.The clustering approach can help policymakers measure economic indices in terms of the factors considered to identify the specific focus of influences on economic development.The results exhibited significant findings for the economic effects of the COVID-19 pandemic on G20 countries,splitting them into three clusters by sharing different measurements and patterns(harmonies and variances across G20 countries).A comprehensive statistical analysis was performed to analyze endogenous and exogenous factors.Similarly,the classification and regression tree method was applied to predict the associations between the response and independent factors to split the G-20 countries into different groups and analyze the economic recession.Variables such as GDP per capita and patient recovery of COVID-19 cases with values of$12,012 and 82.8%,respectively,were the most significant factors for clustering the G20 countries,with a correlation coefficient(R2)of 91.8%.The results and findings offer some crucial recommendations to handle pandemics in terms of the suggested economic systems by identifying the challenges that the G20 countries have experienced.