60kV联合深度学习重建算法在主动脉CT血管造影中的可行性研究

目的:探讨60 kV联合基于深度学习的ClearInfinity(CI)重建算法在主动脉CT血管造影中的可行性。方法:收集2023年7—9月因主动脉疾病在郑州大学第一附属医院拟行主动脉CT血管造影(CTA)的受检者73例,按照随机数字表法分为A组(n=36)和B组(n=37)。A组受检者采用100 kV行常规扫描和重建;B组受检者采用60 kV行CT扫描,再依据重建算法不同分为B1、B2、B3亚组,分别采用30%~90%(间隔30%)CI算法重建,比较各组受检者辐射剂量以及图像质量。结果:除A组和B1组的信噪比(SNR)值在降主动脉、髂总动脉外,其余各组间SNR值比较,差异有统计学意义(均P <0.05)。除A组和B1组在降主动脉层面外,其余各组间对比噪声比(CNR)值比较,差异有统计学意义(均P <0.05)。图像主观评分A组与B2组比较,差异无统计学意义(P> 0.05),A组、B1组和B3组主观评分比较,差异有统计学意义(P <0.05)。结论:对体重指数(BMI)<26 kg/m~2的正常体型受检者,采用60 kV行主动脉CTA能大幅降低辐射剂量,联合深度学习CI重建算法能显著降低图像噪声,改善图像质量以达到诊断需求。

Sacrificial piles as a countermeasure against local scour around underwater pipelines

Local scour around pipelines crossing rivers or in marine environments is a significant concern.It can lead to failure of the pipelines resulting in environmental side effects and economic losses.This study developed an experimental method to reduce local scour around pipelines with a steady flow of clear water by installing cylindrical and cubical sacrificial piles.Three sizes of sacrificial piles were examined in a linear arrangement.Sacrificial piles were installed on the upstream side of the pipeline at three distances.Maximum scour depth reduction rates below the pipeline were computed.The results showed that sacrificial piles could protect a pipeline from local scour.A portion of scoured sediment around the sacrificial piles was deposited beneath the pipeline.This sediment accumulation reduced the scour depth beneath the pipeline.Analysis of the experimental results demonstrated that the size of piles(d),the spacing between piles,and the distance between the pipe and piles(Xp)were the variables that reduced the maximum scour beneath the pipeline with a diameter of D.For the piles with d=0.40D and 0.64D,X_(p)=4OD was the optimal distance to install a group of piles,and cubical piles could mitigate scour more effectively than cylindrical piles under similar conditions.For the piles with d=D,the greatest reduction in scour depth was achieved at X_(p)=50D with any desired spacings between piles,and cylindrical piles in this dimension could protect the pipeline against scour more effectively than cubical piles.

A"messenger zone hypothesis"based on the visual three-dimensional spatial distribution of motoneurons innervating deep limb muscles

Coordinated contraction of skeletal muscles relies on selective connections between the muscles and multiple classes of the spinal motoneuro ns.Howeve r,current research on the spatial location of the spinal motoneurons innervating differe nt muscles is limited.In this study,we investigated the spatial distribution and relative position of different motoneurons that control the deep muscles of the mouse hindlimbs,which were innervated by the obturator nerve,femoral nerve,inferior gluteal nerve,deep pe roneal nerve,and tibial nerve.Locations were visualized by combining a multiplex retrograde tracking technique compatible with three-dimensional imaging of solvent-cleared o rgans(3DISCO)and 3-D imaging technology based on lightsheet fluorescence microscopy(LSFM).Additionally,we propose the hypothesis that"messenger zones"exist as interlaced areas between the motoneuron pools that dominate the synergistic or antagonist muscle groups.We hypothesize that these interlaced neurons may participate in muscle coordination as messenger neurons.Analysis revealed the precise mutual positional relationships among the many motoneurons that innervate different deep muscles of the mouse.Not only do these findings update and supplement our knowledge regarding the overall spatial layout of spinal motoneurons that control mouse limb muscles,but they also provide insights into the mechanisms through which muscle activity is coordinated and the architecture of motor circuits.

Metastatic clear cell sarcoma of the pancreas:A rare case report

BACKGROUND Clear cell sarcoma(CCS)is a rare soft-tissue sarcoma.The most common metastatic sites for CCS are the lungs,bones and brain.CCS is highly invasive and mainly metastasizes to the lung,followed by the bone and brain;however,pancreatic metastasis is relatively rare.CASE SUMMARY We report on a rare case of CCS with pancreatic metastasis in a 47-year-old man.The patient had a relevant medical history 3 years ago,with abdominal pain as the main clinical manifestation.No abnormalities were observed on physical examination and the tumor was found on abdominal computed tomography.Based on the medical history and postoperative pathology,the patient was diagnosed with CCS with pancreatic metastasis.The patient was successfully treated with surgical interventions,including distal pancreatectomy and sple-nectomy.CONCLUSION This report summarizes the available treatment modalities for CCS and the importance of regular postoperative follow-up for patients with CCS.

Neural stem cell-derived exosomes promote mitochondrial biogenesis and restore abnormal protein distribution in a mouse model of Alzheimer's disease

Mitochondrial dysfunction is a hallmark of Alzheimer’s disease.We previously showed that neural stem cell-derived extracellular vesicles improved mitochondrial function in the cortex of AP P/PS1 mice.Because Alzheimer’s disease affects the entire brain,further research is needed to elucidate alterations in mitochondrial metabolism in the brain as a whole.Here,we investigated the expression of several important mitochondrial biogenesis-related cytokines in multiple brain regions after treatment with neural stem cell-derived exosomes and used a combination of whole brain clearing,immunostaining,and lightsheet imaging to clarify their spatial distribution.Additionally,to clarify whether the sirtuin 1(SIRT1)-related pathway plays a regulatory role in neural stem cell-de rived exosomes interfering with mitochondrial functional changes,we generated a novel nervous system-SIRT1 conditional knoc kout AP P/PS1mouse model.Our findings demonstrate that neural stem cell-de rived exosomes significantly increase SIRT1 levels,enhance the production of mitochondrial biogenesis-related fa ctors,and inhibit astrocyte activation,but do not suppress amyloid-βproduction.Thus,neural stem cell-derived exosomes may be a useful therapeutic strategy for Alzheimer’s disease that activates the SIRT1-PGC1αsignaling pathway and increases NRF1 and COXIV synthesis to improve mitochondrial biogenesis.In addition,we showed that the spatial distribution of mitochondrial biogenesis-related factors is disrupted in Alzheimer’s disease,and that neural stem cell-derived exosome treatment can reverse this effect,indicating that neural stem cell-derived exosomes promote mitochondrial biogenesis.

Metastatic clear cell sarcoma of the pancreas:A sporadic cancer

Primary or secondary clear cell sarcoma of the pancreas is an exceedingly rare and aggressive disease.In addition to pathology,molecular analysis is pivotal in differential diagnosis,especially with malignant melanoma.A key aspect in identifying clear cell sarcoma is specific genetic alterations,notably the translocation of t(12;22)(q13;q13),a diagnostic hallmark of this sarcoma subtype,which is absent in malignant melanoma.Treatment of primary clear cell sarcoma of the pancreas is the same as that for adenocarcinoma.

Metastatic clear cell sarcoma of the pancreas:From diagnosis to treatment

This article presents a comprehensive case report on an uncommon instance of metastatic clear cell sarcoma(CCS)originating from the pancreas.The high mortality rate of pancreatic carcinoma underscores the importance of precise diagnosis and early detection.The authors report a novel case of CCS with pancreatic metastasis,detailing successful surgical intervention through distal pancreatectomy and splenectomy,resulting in favourable outcomes.This study highlights the standard role of surgery in treating advanced CCS and emphasizes preoperative imaging and thorough patient history assessment.This article also underscores the necessity for long-term surveillance due to the potential for recurrence or metastasis.Despite the favourable recovery postsurgery,the absence of subsequent follow-up evaluation prompts consideration of the need for extended monitoring.This article raises questions about the nature of the pancreatic lesion and suggests the possibility of a primary lesion.Further evidence is crucial to establish the correlation between the features related to the development of the patient's primary and metastatic tumours.In conclusion,this study offers valuable insights into metastatic CCS of the pancreas,highlighting the importance of regular postoperative follow-up for improved outcomes through early detection and intervention.

Low expression of fatty acid oxidation related gene ACADM indicates poor prognosis of renal clear cell carcinoma and is related to tumor immune infltration

This research aims to identify the key fatty acid beta-oxidation(FAO)genes that are altered in kidney renal clear cell carcinoma(KIRC)and to analyze the role of these genes in KIRC The Gene Expression Omnibus(GEO)and FAO datasets were used to identify these key genes.Wilcoxon rank sum test was used to assess the levels of acyl-CoA dehydrogenase medium chain(ACADM)between KIRC and non cancer samples.The logistic regression and Wilcoxon rank sum test were used to explore the association between ACADM and clinical features.The diagnostic performance of ACADM for KIRC was asessed using a diagnostic receiver operating ch aracteristic(ROC)curve.The co-expressed genes of ACADM were identifed in LinkedOmics database,and their function and pathway enrichment were analyzed.The correlation between ACADM expression level and immune infitration was analyzed by Gene Set Variation Analysis(GSVA)method Additionally,the proliferation,migration,and invasion abilities of KIRC cells were assessed after overexpressing ACADM.Following differential analysis and intersection,we identifed six hub genes,induding ACADM.We found that the expression level of ACADM was decreased in KIRC tissues and had a better diagnostic efect(AUC=0.916).Survival analysis suggested that patients with decreased ACADM expression had a worse prognosis.According to correlation analysis,a variety of dinical features were associated with the expression level of ACADML By analyzing the infiltration level of immune cells,we found that ACADM may be related to the enrichment of immune cells.Finally,ACADM overexpression inhibited proliferation,migration,and invasion of KIRC cells.In conclusion,our findings suggest that reduced ACADM expression in KIRC patients is indicative of poor prognosis.These results imply that ACADM may be a diagnostic and prognostic marker for individuals with KIRC,offering a reference for dinicians in diagnosis and treatment.

Clear cell sarcoma metastasizing to the pancreas

In this editorial based on a case report,we delve into a seldom-seen occurrence of clear cell sarcoma featuring pancreatic metastasis in a 47-year-old male patient.Recognized for its typical tendency to metastasize to the lungs,bones,and brain,clear cell sarcoma rarely extends its reach to the pancreas.Despite the initial absence of discernible abnormalities during the patient's physical examination,the manifestation of abdominal pain prompted further investigation.Subsequent abdominal computed tomography brought to light the presence of a pancreatic tumor,culminating in the definitive diagnosis of clear cell sarcoma with pancreatic metastasis.The successful management of this atypical presentation involved a series of surgical interventions,including distal pancreatectomy and splenectomy.This report not only sheds light on the infrequent manifestation of clear cell sarcoma within the pancreas but also underscores the pivotal role of vigilant postoperative follow-up in addressing this rare sarcoma.The emphasis on postoperative care serves as a crucial aspect of the broader narrative,acknowledging the need for ongoing monitoring and management to ensure a comprehensive and successful treatment trajectory for patients with this unique presentation of clear cell sarcoma.

Left lower lobe sleeve resection for the clear cell variant of pulmonary mucoepidermoid carcinoma:A case report

BACKGROUND Pulmonary mucoepidermoid carcinoma(PMEC)is a rare malignancy that arises from minor salivary glands within the tracheobronchial tree.The clear cell variant of PMEC is exceptionally uncommon and presents notable diagnostic challenges,primarily attributable to its morphological similarity to other tumors containing clear cells.CASE SUMMARY A 22-year-old male,formerly in good health,came in with a two-month duration of persistent cough and production of sputum.Subsequent imaging and bronchoscopy examinations revealed a 2 cm tumor in the distal left main bronchus,which resulted in complete atelectasis of the left lung.Further assessment via positron emission tomography/computed tomography scans and endoscopic biopsy confirmed the primary malignant nature of the tumor,charac-terized by clear cell morphology in most of the tumor cells.The patient underwent a left lower lobe sleeve resection accompanied by systematic mediastinal lymph node dissection.Molecular pathology analysis subsequently revealed a CRTC3-MAML2 gene fusion,leading to a definitive pathological diagnosis of the clear cell variant of PMEC,staged as T2N0M0.After surgery,the patient experienced a smooth recovery and exhibited no signs of recurrence during the one-and-a-half-year follow-up period.CONCLUSION This article describes an unusual case of a clear cell variant of PMEC characterized by the presence of a CRTC3-MAML2 gene fusion in a 22-year-old male.The patient underwent successful left lower lobe sleeve resection.This case underscores the distinctive challenges associated with diagnosing and treating this uncommon malignancy,underscoring the importance of precise diagnosis and personalized treatment strategies.

A Study on the Influence of Social Media Use on Psychological Anxiety among Young Women

To explore the relationship between social influence,social comparison,clarity of self-concept,and psychological anxiety among young women during their usage of social networking sites,our study selected 338 young women aged 14-34 from the social site platforms of Little Red Book and Weibo for questionnaire surveys.The Passive Social Network Utilization Scale,Social Comparison Scale(SCS),Social Influence Questionnaire,Self-Concept Clarity Scale(SCCS),and Generalized Anxiety Disorder Scale(GAD-7)were employed to measure the subjects.Our results show that the frequency of passive social media use is positively related to the level of psychological anxiety.Social comparison,social influence,and unclear self-concepts under social media use are negatively predictive of psychological anxiety.The chain mediation effects indicate that social comparison and social influence under social media use negatively predict the clarity of self-concept,thus having a negative impact on the psychological health of young women.Therefore,young women should strengthen their self-concepts,control their frequency of social media usage,avoid addiction,and pay special attention to their frequency of passive use,in order to protect their psychological health.Our study provides some practical implications and insights regarding the relationship between young women’s social media use and psychological health.

Economy Function in the Mode of Sustainable Development

To implement the previously formulated principles of sustainable economic development, all solutions of the linear system of equations and inequalities, which are satisfied by the vector of real consumption, are completely described. It is established that the vector of real consumption with the minimum level of excess supply is determined by the solution of some quadratic programming problem. The necessary and sufficient conditions are established under which the economic system, described by the “input-output” production model, functions in the mode of sustainable development. A complete description of the equilibrium states for which markets are partially cleared in the economy model of production “input-output” is given, on the basis that all solutions of system of linear equations and inequalities are completely described. The existence of a family of taxation vectors in the “input-output” model of production, under which the economic system is able to function in the mode of sustainable development, is proved. Restrictions were found for the vector of taxation in the economic system, under which the economic system is able to function in the mode of sustainable development.

Network pharmacology and molecular docking analysis reveal insights into the molecular mechanism of Gualou Qumai Wan in clear cell renal cell carcinoma

Background:To initially clarify the potential therapeutic targets and pharmacological mechanism regarding Gualou Qumai Wan(GQW),a kind of traditional Chinese medicine(TCM),in clear cell renal cell carcinoma(ccRCC)by virtue of the network pharmacology analysis and molecular docking analysis.Methods:The screening of bioactive components and targets of GQW was based on the Traditional Chinese Medicine System Pharmacology(TCMSP)and the UniProt platform served for standardizing their targets.Online Mendelian Inheritance in Man(OMIM),PharmGkb,TTD,DrugBank and GeneCards databases were searched to collect the disease targets of ccRCC.Cytoscape assisted in constructing herb-compound-target(H-C-T)networks.The STRING database was searched for constructing the target protein-protein interaction(PPI)networks,while the R programming language served for analyzing GO functional terms and the KEGG pathways related to potential targets.Analyses of core genes related to survival and tumor microenvironment(TME)were conducted respectively based on the GEPIA2 database and TIMER 2.0 database.Human Protein Atlas(HPA)and The Cancer Genome Atlas(TCGA)helped to obtain core genes’protein expression as well as transcriptome expression level.Autodock Vina software validated the molecular docking regarding GQW components and pivotal targets.Results:The constructed H-C-T networks mainly had 33 compounds and 65 targets.A topological analysis of the PPI network identified that ESR1,AKT1,HIF1A,PTGS2,TP53 and VEGFA serve as core targets in the way GQW affects ccRCC.According to the GO and KEGG pathway enrichment analyses,the effects of GQW are mediated by genes related to hypoxia and oxidative stress as well as the Chemical carcinogenesis-receptor activation and PI3K-Akt signaling pathways.AKT1 shows a close relation to the recruitment of various immune cells and can remarkably affect disease prognosis according to reports.Molecular docking and molecular dynamics simulations showed that diosgenin has higher affinity with core targets.Conclusion:The study makes a comprehensive explanation of the biological activity,potential targets,as well as molecular mechanism regarding GQW against ccRCC,which promisingly assists in revealing the action mechanism of TCM formulae in disease treatment and the respective and scientific basis.

Estimation of Daily Global Solar Radiation with Different Sunshine-Based Models for Some Burundian Stations

Sunshine duration (S) based empirical equations have been employed in this study to estimate the daily global solar radiation on a horizontal surface (G) for six meteorological stations in Burundi. Those equations include the Ångström-Prescott linear model and four amongst its derivatives, i.e. logarithmic, exponential, power and quadratic functions. Monthly mean values of daily global solar radiation and sunshine duration data for a period of 20 to 23 years, from the Geographical Institute of Burundi (IGEBU), have been used. For any of the six stations, ten single or double linear regressions have been developed from the above-said five functions, to relate in terms of monthly mean values, the daily clearness index () to each of the next two kinds of relative sunshine duration (RSD): and . In those ratios, G0, S0 and stand for the extraterrestrial daily solar radiation on a horizontal surface, the day length and the modified day length taking into account the natural site’s horizon, respectively. According to the calculated mean values of the clearness index and the RSD, each station experiences a high number of fairly clear (or partially cloudy) days. Estimated values of the dependent variable (y) in each developed linear regression, have been compared to measured values in terms of the coefficients of correlation (R) and of determination (R2), the mean bias error (MBE), the root mean square error (RMSE) and the t-statistics. Mean values of these statistical indicators have been used to rank, according to decreasing performance level, firstly the ten developed equations per station on account of the overall six stations, secondly the six stations on account of the overall ten equations. Nevertheless, the obtained values of those indicators lay in the next ranges for all the developed sixty equations:;;;, with . These results lead to assert that any of the sixty developed linear regressions (and thus equations in terms of and ), fits very adequately measured data, and should be used to estimate monthly average daily global solar radiation with sunshine duration for the relevant station. It is also found that using as RSD, is slightly more advantageous than using for estimating the monthly average daily clearness index, . Moreover, values of statistical indicators of this study match adequately data from other works on the same kinds of empirical equations.

Clear Cell Pleomorphic Dermal Sarcoma: A Case Report and Literature Review

Introduction: Atypical fibroxanthoma (AFX) and pleomorphic dermal sarcoma (PDS) are one spectrum of rare cutaneous neoplasms that typically arise in sun-exposed skin of older population. AFX/PDS is essentially diagnosis of exclusion requiring Immunohistochemical work-up to exclude other types of tumors. Case Report: We present a case involving an ulcerated solitary lesion on the scalp of an elderly man. Histological examination revealed that the dermal tumor was composed of large pleomorphic, epithelioid, and spindle cells with clear cytoplasm. These cells were negative for cytokeratins, melanocytes and smooth muscle markers, but positive for CD10. These findings are consistent with a diagnosis of clear cell (CC) PDS. Conclusion: PDS is a low-grade malignancy that can recur locally and metastasize, which is distinguished from AFX by its larger size and the presence of aggressive histopathologic features including deeper invasion into the subcutaneous tissue, tumor necrosis, and lymphovascular and/or perineural involvement. Among several histopathologic variants, the CC variant is extremely rare with only two cases of PDS reported in the literature to date.

Extinction event that wiped out dinosaurs cleared way for modern frogs

Subject Code:C04With the support by the National Natural Science Foundation of China,a collaborative study by Chinese and American biologists led by Prof.Zhang Peng(张鹏)from Sun Yat-Sen University shows that nearly nine out of 10species of frog today have descended from just three lineages that survived the

4 New York City Policemen Cleared in Diallo Murder

去年2月4日凌晨,来自几内亚的22岁移民迪亚洛在纽约布朗克斯区自己的寓所门口被4名值勤的白人警察连击41枪,身中19弹当场惨死。此案当时立即引发了纽约市各界数万人的大游行。随后,当地检察机关以二级谋杀罪、危害公众安全等6项罪名对这4名白人警察提出起诉。今年1月31日,纽约州高等法院开庭审理此案并组成了由4名黑人和8名白人组成的陪审团。在经过3天的商讨后,陪审团在纽约州首府奥尔巴尼宣布,指控4名白人警察的6项罪名均不成立。 判决宣布后,纽约市接连爆发了有数千名各阶层民众参加的各种示威活动,抗议白人警察对少数族裔移民滥用暴力和种族歧视倾向,由这一裁决引发的纽约各种族之间的紧张关系也有愈演愈烈之势。 本文从内容到表达,有许多值得读者回味之处。比如: 1/The racially mixed crowd of mostly young people chanted.“No Justice,NoPeace.”(句中的短语racially mixed crowd告知读者:游行示威队伍中不乏白人青年。) 2/Angry but nonviolent(非暴力的)demonstrations in Albany and in theSoundview section of the Bronx(布朗克斯,纽约市最北端的一区)where Diallolived and was killed began even as the verdicts were being read in court and broad—cast live on television and

Is the soil seed bank a reliable source for passive restoration of bush-cleared semi-arid rangelands of South Africa?

Background:Bush clearing of encroached rangelands is crucial for restoration of herbaceous cover and diversity.Regeneration after bush clearing depends largely on the soil seed bank(SSB)size and composition.To assess the potential of the SSB to facilitate post-clearing herbaceous restoration,we examined the SSB density,composition and diversity and similarity between SSB and aboveground vegetation(AGV).Methods:The study was conducted in semi-arid rangelands of Maseding and Kgomokgomo in North-West Province of South Africa.In each rangeland,all woody plants in three 1250 m^(2) plots were cut using saws and loppers,with the stumps treated with picloram.Paired observations were conducted in cleared and uncleared microsites.Soil samples were collected at three depths(0-10,10-20 and 20-30 cm)in each microsite in April(pretreatment),August,October and December 2016 and in April and August 2017.SSB was assessed using seedling emergence method,whereas pre-and post-clearing surveys of AGV were conducted in February 2016 and 2017,respectively.Results:Cleared microsites had significantly(p<0.01)higher seed bank densities(1872 and 693 seeds m^(-2) at Maseding and Kgomokgomo,respectively)relative to uncleared microsites in August 2017,with grasses accounting for higher densities than other plant functional groups in the upper 0-10 cm.Pioneer grasses(Aristida congesta subsp.barbicollis,Brachiaria eruciformis and Tragus berteronianus)and invasive forbs(Bidens pilosa and Schkuhria pinnata)dominated the SSB in cleared microsites at Maseding,whereas succulents(Portulaca spp.)and pioneer grasses(T.berteronianus and Urochloa mosambicensis)were abundant at Kgomokgomo in August 2017.SSB and AGV were dissimilar until December 2016;thereafter,similarity increased significantly(p<0.05)in cleared microsites(Sørensen’s coefficient=0.60 to 0.66 at Maseding and 0.43 to 0.52 at Kgomokgomo)compared to uncleared microsites.Species diversity was highest in August 2016 and April 2017 at Maseding,but it did not differ between two microsites(p>0.05).At Kgomokgomo,SSB was more diverse in cleared than uncleared microsites in April and August 2017.Conclusion:High seed bank densities in the upper soil layer in cleared microsites would promote passive restoration,but regeneration is likely to be initiated by early successional species.However,close monitoring and eradication of invasive forbs and succulents is necessary following bush clearing.The tendency of SSB resembling AGV over time in cleared microsites signifies that seed production from AGV is important for passive restoration following bush clearing.

大气光学湍流模式研究:C_(n)^(2)廓线模式

由于大气湍流的存在,当光束在大气中传播时会发生相位起伏、光强闪烁等一系列湍流效应现象,严重制约光电系统的性能,是造成天文观测困难的主要原因.大气折射率结构常数C_(n)^(2)廓线是评估大气湍流效应的重要参数.本文归纳了几种有代表性的C_n~2廓线模式,提出了修正的CLEAR I夜晚模式;分析了高美古、拉萨、大柴旦、茂名、荣成等5个实验点探空测量数据,给出了5个实验点算术平均拟合的C_(n)^(2)廓线公式;计算了各模式和测量数据在波长为0.5μm时的大气相干长度r0、视宁度εFWHM、等晕角θ0、相干时间τ0、等效高度h和等效风速V等大气光学参数以及各大气层C_(n)^(2)递减率和不同大气层湍流贡献百分比.重点对H-V(5/7)模式的存疑、C_(n)^(2)廓线模式采用的平均方法、低平流层C_(n)^(2)是否具有统一的递减率等问题进行讨论并给出答案.

Overcast sky condition prevails on and influences the biometeorology of the tropical Andean Páramos

Clouds play a major role in modulating the biometeorological processes. We studied the influence of cloudiness on four biometeorological variables:daily air temperature(Tair), relative humidity(RH),reference evapotranspiration(ETr),and photosynthetic active radiation(PAR), recorded at four sites of Andean Páramos in southern Ecuador during 2.5 to 5.5 years. First, we quantified both the cloud cover percentage(Cloud%) creating cloud masks over the visible bands of Landsat 7 images and the sky condition(K_(T)) using the records of solar and extraterrestrial radiation. Second, we estimated KTfrom Cloud%. Finally, we quantified T_(air), RH, ET_(r), and PAR under clear, cloudy, and overcast K_(T) and their dependence on KT. The average Cloud% ranged between 65%–76%, and KTcorroborated the prevailing overcast sky(between 55% and 72.5% of the days) over the páramos. The proposed model performed well in the sites of calibration(R^(2)= 0.80;MBE = 0.00;RMSE = 0.05) and validation(R^(2)= 0.74;MBE =-0.07;RMSE = 0.11). The overcast sky diminished T_(air)(≤ 10℃), ET_(r)(≤ 1.6 mm day-1), and PAR(4 MJ m^(-2)day^(-1)) and increased RH(≥ 88%),while the variables showed the opposite behavior during the uncommon clear sky(≤ 5.5% of the days).Thus, mostly the dynamic of RH(R^(2)≥ 0.62), ETr(R^(2)≥ 0.85), and PAR(R2≥ 0.77) depended on K_(T). Hence,the prevailing overcast sky influenced the biometeorology of the páramos.