bluuebunny/crossref_metadata_2025 huggingface dataset:
Efficacy of Cissus Quadrangularis (Hadjod) Used Locally, Systemically and combination of both as an Adjunct to Osteon II and PRF in Class II Furcation Defects: A Protocol for Clinical and Radiographic Study
Authors: Durge Khushboo , Jaiswal Priyanka , Wanjari Anita , Shirbhate Unnati
Published: October 2024

Introduction: When there is significant furcation involvement, mechanical debridement without surgery can cause the disease to progressively worsen. To halt the disease process, surgery allows for odontoplasty, root debridement, osseous recontouring, and periodontal regeneration while preserving periodontal attachment. Need of the Study: In cases of furcation deficiencies, periodontal regeneration with different bone grafts is an effective method to both replace lost bone tissue and slow down the progression of the disease. In osseous abnormalities, the additive actions and features of Cissus Quadrangularis (CQ) demonstrate improved healing. Thus, the purpose of present clinical trial is to determine whether the combination of CQ, when utilised locally and systemically, is efficacious for the management of Class II furcation defects. Aim: To evaluate and compare the efficacy of CQ (Hadjod) used locally, systemically, and in combination as an adjunct to osteon II with Platelet Rich Fibrin (PRF) for the management of Class II furcation defects. Methodology: A randomised clinical trial will be conducted in the Department of Periodontics at Sharad Pawar Dental College, Datta Meghe Institute of Higher Education and Research (DMIHER), Wardha, Maharashtra, India from April 2024 to March 2026. A total 60 systemically healthy individuals with Class II furcation invasions, either buccal or lingual, and moderate to severe chronic periodontitis will be selected. The study population will be categorised into three interventional groups and one control group as follows: Group A: Control group (n=15) will be treated with osteon II + PRF membrane + antibiotic coverage for Class II furcation defects, Group B: (n=15) will be treated with osteon II + PRF membrane + CQ graft (locally) for Class II furcation defects + antibiotic coverage, Group C: (n=15) will be treated with osteon II + PRF membrane + systemic dosage of CQ for Class II furcation defects + antibiotic coverage, Group D: (n=15) will be treated with osteon II + PRF membrane + CQ graft (locally) + systemic dosage of CQ for Class II furcation defects + antibiotic coverage. The data will be analysed and calculated using the Student’s t-test, with a significance level of less than 0.05.
Comparative Evaluation of Conventional Nasolabial Flap with and without Fishtail Modification in Patients with Oral Submucous Fibrosis: A Research Protocol
Authors: Wadhwani Nikhar Shyam , Bhola Nitin Dharampal
Published: October 2024

Introduction: Oral Submucous Fibrosis (OSMF) is a longterm condition characterised by the gradual buildup of fibrous tissue in the oral cavity, often extending to the throat and upper oesophagus. The primary symptoms include progressive limitation in mouth opening due to the formation of stiff fibrous bands in the oral mucosa, accompanied by muscle atrophy. However, the most concerning aspect of this restriction, known as trismus, is its hindrance to effective cancer monitoring. Surgical approaches typically aim to release these fibrotic bands, while medical interventions focus on managing inflammation and preventing further fibrosis. Need of the Study: A modification of the nasolabial flap has been suggested for the reconstruction of intraoral defects following ablative surgery for OSMF. The study will assess its merits in comparison to the conventional nasolabial flap. Aim: To evaluate and compare the aesthetic and functional outcomes of the rima oris between the Conventional Nasolabial Flap and the Nasolabial Flap with Fishtail Modification in patients undergoing surgical intervention for OSMF. Materials and Methods: A prospective, double-blinded, randomised controlled trial will be conducted in the Department of Oral and Maxillofacial Surgery at Acharya Vinoba Bhave Rural Hospital, associated with Jawaharlal Nehru Medical College, Wardha, Maharashtra, India, from November 2023 to November 2024. Patients older than 18 years of age diagnosed with OSMF, without any superimposing cancerous lesions, will be included in the study. They will be divided into two groups: Group A will be treated with bilateral fibrotomy, coronoidotomy and reconstruction with the conventional nasolabial flap, while Group B will undergo the same surgical intervention, except that the reconstruction will be performed using the fishtail modification of the nasolabial flap. The parameters that will be compared include interincisal mouth opening, intercommissural width, dehiscence and flap necrosis. The analysis will be conducted using the Chi-square test and Fisher’s-exact test for categorical data and the independent t-test for continuous data that follow a normal distribution. These statistical tests will help evaluate the association between different demographic, clinical and etiological factors and the outcomes under consideration. A p-value of <0.05 will be considered statistically significant.
Retrievability of Intracanal Medicament from Root Canals: An In-vitro CBCT Volumetric Analysis
Authors: Choudhary Deebah
Published: October 2024

Introduction: The complete removal of Calcium Hydroxide {Ca(OH)2 } using various techniques remains a challenge in root canal therapy. One of the most commonly used methods for removing calcium hydroxide is by using a Master Apical File (MAF) along with sodium hypochlorite and Ethylenediaminetetracetic Acid (EDTA). Various new modalities, like Canal Brush, NaviTip and file systems, have emerged to tackle the residual calcium hydroxide in the canal; but none of these methods have been able to completely remove it from the canal. Aim: To evaluate and compare the efficacy of H-files, NaviTip FX and Canal Brushes in removing calcium hydroxide intracanal medicament from root canals. Materials and Methods: This in-vitro study was carried out in the Department of Conservative Dentistry and Endodontics at KM Shah Dental College and Hospital, Vadodara, Gujarat, India, from December 2023 to March 2024. To standardise the length at 14 mm, 30 mandibular premolar teeth (n=30) with a single root were decoronated at the Cementoenamel Junction (CEJ). The working length was determined, followed by the cleaning and shaping of all specimens using ProTaper Rotary Files. Intracanal medicament (Metapex) was placed and the canals were sealed with Glass Ionomer Cement (GIC). The specimens were then placed at 37±1ºC and 100% relative humidity for 30 days. The medicament was subsequently removed by three different protocols: H-file, NaviTip FX and Canal Brush (n=10 each). The residual volumes in the mesial, distal and apical thirds were assessed, referring to the volume of medicament left in the canal, which was measured using Cone-beam Computed Tomography (CBCT). The recorded variables were analysed using one-way Analysis of Variance (ANOVA) post-hoc tests (p<0.05). Results: The Canal Brush removed the maximum amount of Metapex in the apical third (0.108) of the roots of the premolars, followed by NaviTip FX and then H-file. In the middle third of the root, NaviTip FX removed more Metapex than the Canal Brush, followed by H-files. A comparison of retrieval between and within the groups it showed that none of the techniques were capable of removing all the Metapex from the specimens, with p>0.05. Conclusion: The present study demonstrated that the Canal Brush showed superior results in retrieving Metapex from the apical third of the root and the distal side (middle third), whereas NaviTip FX removed more Metapex from the mesial side (middle third) of the root, but H-file exhibited the least efficacy in the retrieval of Metapex. Total removal of calcium hydroxide from the entire canal is not possible regardless of the technique used.
Higher Agricultural Education: An Exploratory Study on Skill Gap of Students
Authors: K. R. Ananda , Satyapriya  , Bishnoi Sitaram , Y. H. Preeti , Pal Ankit , Shravani Kotha
Published: October 2024

The skill gap among higher education students has become a pressing concern in today's competitive job market, prompting the need for thorough assessment and targeted interventions. This study endeavours to quantify the extent of skill discrepancies among students in higher agricultural education. Through skill gap analysis, the aim is to gauge the shortfall in agricultural and professional competencies among young scholars, delineating the areas where skills are lacking or underdeveloped. By employing an exploratory research design, the study seeks to identify and address skill gaps effectively. The target respondents comprise students from IARI, University of Agricultural Sciences (Raichur), and Banda University of Agriculture and Technology, with a sample size of 150 selected to represent the population adequately. To construct the skill gap index, various dimensions including technical, personal, problem-solving, leadership, entrepreneurial, computer, and organizational skills were pretested. Data collection involved the utilization of questionnaires and in-person interviews to evaluate competency differences among students across the three agricultural universities. Statistical methods such as the Friedman test and the Wilcoxon signed rank test was employed to analyse the gathered data. The analysis found significant disparities in the overall skill levels of students. These findings underscore the need for targeted interventions to bridge the identified skill gaps effectively. By illuminating areas of deficiency, this study provides valuable insights for enhancing the quality of agricultural education and fostering the development of well-rounded professionals equipped to tackle the challenges of the agricultural sector.
Assessment of Farmers Knowledge Level on Turmeric Cultivation Practices
Authors: C Dhivya , R Arunkumar , R Muthukumar
Published: October 2024

Turmeric (Curcuma longa), one of the oldest known medicinal plants, has been used for centuries due to its significant health benefits. Curcumin, the primary bioactive compound found in turmeric, belongs to the Zingiberaceae family and is well-documented for its antibacterial, antifungal, renal, and hepatoprotective properties. This study was conducted in the Kodumudi block of Erode District, Tamil Nadu, due to its extensive turmeric cultivation. A sample of 120 farmers was selected to assess their knowledge of recommended turmeric cultivation technologies. The results indicated that the turmeric growers possessed a medium level of knowledge regarding the recommended practices for turmeric cultivation. The research employed an analytical approach to assess farmers' understanding of key practices including main field preparation, planting techniques, nutrient management, and pest and disease control. The findings reveal that while growers displayed strong knowledge in areas such as seasonal practices, irrigation, and spacing, there were significant gaps in their understanding of rhizome treatment, micronutrient application, and pest management. Specifically, knowledge about managing pests such as rhizome scales, leaf rollers, and shoot and root borers was notably lacking. The study highlights the need for targeted training and educational programs to address these gaps, particularly in pest identification and control measures. By enhancing farmers' knowledge in these critical areas, the study aims to improve turmeric cultivation practices and contribute to the sustainability of turmeric farming in Erode District.
Organizational Workforce Management in the Digital Age: The Role of Technocultural Interventions in Mitigating the Negative Impacts of AI-Driven Technological Change
Authors: Joseph Sunday Abayomi
Published: October 2024

This study explores the impact of AI-driven technological change on workforce management, focusing on job displacement, employee satisfaction, and productivity. A mixed-method approach was employed, including logistic regression, K-means clustering, and multivariate regression analysis, to evaluate the effectiveness of technocultural interventions (upskilling programs, ethical AI frameworks, and innovation culture). Data was sourced from the U.S. Bureau of Labor Statistics (BLS) and survey questionnaires. Logistic regression revealed that routine AI adoption showed a weak positive relationship with job displacement (B = 0.013, p = 0.111), but the overall model was not statistically significant. The K-means clustering identified three distinct organizational patterns in adopting technocultural interventions. Multivariate regression highlighted the substantial role of leadership commitment in increasing employee satisfaction (B = -0.067, p = 0.039) but found limited direct effects of upskilling programs and AI frameworks on productivity. Based on the findings, the study highlights the importance of customized, sector-specific interventions and recommends that organizations integrate leadership and ethical considerations to manage AI-driven changes effectively.
Perception of Educated Unemployed Rural Youth towards Entrepreneurial Activities for Self-employment
Authors: Parvez Md. Asif , Kanungo Aditya Prasad , Sahoo Sweta , Mohanty Smaranika , Sahu Karishma
Published: October 2024

For establishing any enterprise, the perception of respondents towards various aspects regarding the entrepreneurial activities plays an important role to establish positive thoughts and approaches to be an entrepreneur. Therefore, perception study pays a significant role in this regard. In this study an attempt has been made to understand the perception of respondents regarding socio cultural environment, family support, fear to engage in entrepreneurship. The current study was carried in Khordha district of Odisha covering 2 blocks namely Banpur and Tangi, 16 villages were selected and a total of 120 respondent’s response were recorded based on a pre-tested interview schedule. The respondents were selected by proportionate random sampling method.
Efficacy and Residual Analysis of Three Insecticides against Spodoptera littoralis (Boisd.) on Field-grown Tomatoes
Authors: A. A. El-Ghanam, , Abdo Ekram, A. , Samir Sara , Abdel-aziz A.A. , Elsarand E.A.
Published: October 2024

Spodoptera littoralis (Boisd.) is among the most destructive insect pests in Egypt, the field study was conducted at El-Beheira Governorate, Egypt to evaluate the toxicity of three insecticides against 2nd and 4th larval instars of these insect and residual effect in tomato fruit into open field application. The outcomes demonstrated that spinosad, methoxyfenzide and diflubenzuron proved to be very toxic. Semi-field application showed that spinosad was the most effective with 91.38 % and 100% insect pest mortalities at initial and residual effects against second instar larvae, respectively.  The initial effect manifested higher morality (90.25%) for fourth instar larvae when treated with diflubenzuron followed by spinosad (86.50%), then methoxyfenzide (84.25%), while the residual effects of all tested insecticides were 100% mortality. The findings additionally demonstrated that the pre-harvest intervals (PHI) for diflubenzuron, spinosad, and methoxyfenzide were 3,7 and 10 days, respectively, for tomato fruits. Following this PHI, the products are considered safe for export and local consumption, as the residue level satisfies the maximum residue limit, which is the level documented by the European Union.
Potential Impacts of Green Manure Incorporation on Soil Fertility Enhancement and Rice Yield
Authors: Way May Phyoe , Ngwe Kyaw , Soe Yinn Mar , Moe Kyi
Published: October 2024

Soil green manure amendment is a potential agricultural practice for soil fertility management and conservation of ecosystem. Common green manure plants such as sunn hemp, dhaincha and pulses have different nature and ability to contribute essential nutrients for plant growth and carbon sequestration.  Those plants are ultimately serving as a supplement or replacement for chemical fertilizers. Producing of nutrients from green manure amendment by decomposition and mineralization processes is influenced by quantity & quality of green manure and soil properties. Therefore, management of green manure to be efficient and synchronize crop demands is essential. Management on days to harvest, incorporation days into soil and amount of green manure is based on its C/N ratio and biomass obtained which are changing with the age. Rice is major crop and ultimately producing in topical Asia and the it is increasing to meet the demands of increasing population. The study focused on green manure amendment and its impact on rice yield. Incorporation of green manure enhances nitrogen and carbon balance in the soil while decreasing the need for chemical fertilizer applications, ensuring to improve rice yields. Rice yield by the application of only green manure 20 ton/ha application was 90% higher than that without nutrient application.  Then, combine application of sunn hemp and chemical nitrogen fertilizer increases rice yield 8-17% than the only chemical nitrogen fertilizer. By combination of green manure 20 ton/ha and chemical N fertilizer 60 kg/ha produced higher yield than only double chemical N fertilizer rate of 120 kg/ha. Similarly, the synergistic effect of organic compost and green manure significantly increased the benefits of green manure alone. In terms of soil fertility, green manure amendment provides plant essential nutrients and improve physical and biological properties as well. Therefore, the practice of green manuring shows promising potential for positively influencing soil health, thereby contributing to the sustainability of crop yields.
Determination of PAHs in Surface Sediments along Dakar Coast Using QuECHERS and Gas Chromatography Coupled to Tandem Mass Spectrometry
Authors: Cisse Dame , Ndiaye Birame , Dione Cheikh Tidiane , Diagne Ibrahima , Hane Maoudo , Dione Mame Mor , Diouf Sitor , Sarr Mamadou , Ka Ousmane , Millet Maurice , Ndiaye Momar , Ba Seydou
Published: October 2024

Untreated sewage, which is a source of many pollutants, can also deposit a mass of sediment on beaches. These sediments can trap many pollutants, including PAHs, which are toxic and mutagenic to DNA and RNA in organisms. In this study, we investigated the contamination of sediments from the beaches of Hann, Soumbédioune and Ngor on the coast of Dakar by the 16 priority PAHs identified by the US Environmental Protection Agency (EPA). The sediment samples were taken between June and September 2018. Analyses were carried out using the GC-MS technique in tandem mode. For extraction and purification, QuECHERS and dSPE RESTEK salts were used, respectively, with recoveries ranging from 83.87 to 98.10%. For PAH repeatability, the %RSD values ranged from 0.02 to 3.08%, while those obtained for reproducibility varied from 0.01 to 1.29%. The results show that the highest levels were recorded in September: pyrene with 35.763 µg.Kg-1, benzo(a)anthracene (22.396 µg.Kg-1) and benzo(k)fluoranthene (18.678 µg.Kg-1) in Hann. At Soumbédioune, dibenzo(a,h)anthracene is at 15.782 µg.Kg-1 and at Ngor coronene has the highest content (9.030 µg.Kg-1). Analysis of the Shapiro-Wilk normality test reveals that most of the p-values for the variances of the various PAHs are above the 5% threshold. For the Levene test, apart from pyrene, the rest of the hydrocarbons satisfied the heteroscedacity hypothesis (inequality of at least two variances) with p-values below the 5% threshold.
Squamous Cell Papilloma on the lip: A Rare Case Report
Authors: Agarwal Aishwarya , Nandini Ambika , V.Setty Jyothsna. , Chowdhary Nagalakshmi , Veena.S  , Sharmila.D
Published: October 2024

Squamous cell papilloma, is a benign, soft, cauliflower-like growth caused due to the rapid proliferation of the stratified squamous epithelium in the oral cavity. Its etiology is not exactly known but it is generally associated with infection Human Papilloma Virus (HPV), trauma /irritation, Immunocompromised status, lifestyle, and habits (tobacco use, alcohol consumption, etc.), poor diet and psychological factors. It predominantly occurs in middle age and in can also be seen in children accounting to 8% of all oral tumours in children. This case report sheds light on one such case of a 14 -year female patient with a white growth on the upper lip.
Comparative Study of the Efficacy of Two Biological Insecticides (Azadirachta indica and Bacillus thuringiensis) and a Chemical insecticide (Diflubenzuron WP) against Fall Armyworm, Spodoptera frugiperda (Lepidoptera: Noctuidae) in Maize Crop, Western Bur
Authors: Ouattara Delphine , Tiendrébéogo Fabien Kis-Wend-Sida , Rabiéta Simdé , Kossi Latevi , Yaméogo Innocent Sibiri , Yaméogo Eutich U. W. , Sadia Hervé , Nacro Souleymane
Published: October 2024

Aims: This study aimed at comparing the biological efficacy of Diflubenzuron WP, a chemical insecticide, and two biopesticides, one based on neem oil (Azadirachta indica) and an entomopathogen (Bacillus thuringiensis) against the fall armyworm on maize.
Place and Duration of Study: The work was carried out on the irrigated scheme of Bama, western Burkina Faso during the 2022 and 2023 wet seasons.
Methodology: The experimental design was a Fisher block with 4 treatments: T0: untreated or control; T1: Bacillus thuringiensis; T2: neem oil; T3: Diflubenzuron WP, in 4 replications. Entomological observations focused on the score and severity of attacks, as well as the pest's infestations rate.
Results: The results showed that the different insecticides tested over the two wet seasons of 2022 and 2023 induced better control of S. frugiperda populations, with larval density being kept lower with the treatment of Diflubenzuron WP (4.25±1.2%), neem oil (14.28±1.6%) and Bacillus thuringiensis (24.5±3.2%). The insect damage severity rates and scores of damaged ears were also low for the three treatments respectively (1.09±0.2, 0.9±0.26 and 0.27±0.71) over the two cropping seasons. Diflubenzuron WP insecticide treatment not only reduced pest pressure, but also significantly improved maize yield.  No surprisingly the highest yield (5.14 t/ha) was recorded with Diflubenzuron WP, followed by neem oil (4.62kg/ha) and finally Bacillus thuringiensis (3.92kg/ha).
Conclusion: Further studies are needed to determine the optimal doses of neem oil and Bt for the control of Fall Armyworm. Neem oil can be considered as a good alternative to a chemical insecticide like Diflubenzuron WP.
Evaluating the Yield Performance of Released Sesame Varieties in Western Tigray, Northern Ethiopia
Authors: Geremedhin Zerabruk
Published: October 2024

The experiment was conducted in western Tigray in Humera and Dansha (Kebabo) area during the main growing season of 2016 under rain fed condition with the aim of evaluating and identifying the well performing and high yielder sesame variety. The experiment consisted of nine varieties laid down in randomized complete block design (RCBD) with three replications, Result of the combined analysis showed highly significant (p<0.01) difference among the varieties in days to flowering, days to maturity, number of branches per plant, number of pods per plant, thousand seeds weight and grain yield. Among the nine sesame varieties the highest mean grain yield was recorded on Setit-2 (1111.89 kg ha-1), Setit-1 (1070.58 kg ha-1), Humera-1(976.42 kg ha-1) and local check (970.20 kg ha-1) followed by Adi (755.42 kg ha-1) whereas the lowest mean grain yield was recorded on Borkena (548.67 kg ha-1), BaHa - Zeyit  (548.69 kg ha-1) followed by BaHa- Necho (616.28 kg ha-1) and Gonder-1 (683.09 kg ha-1). This indicated that the verities released by Humera Agricultural Research Center and the local check (Hirhir) were highly performed in Humera. Therefore, even though they were statically similar; Setit-2 was recently released and it can be concluded that variety Setit-2 well performed and can be recommended for the growers in the study area.
Studies on Effect of Genotypes and Planting Time on Growth and Corm Characters of Gladiolus
Authors: Singh S.R.P. , Singh A.P. , Kumar Vijay , Tiwari Divya , Pal Mahender , Yadav Pankaj , Ojha M.D.
Published: October 2024

Gladiolus is an important cut flower crop, grown commercially in many parts of the globe. This flower has gained popularity owing to its incomparable beauty, attractive colours, various sizes and shapes of florets, variable spike length and long vase life. Gladiolus produces beautiful spikes from December to March in the plains and from June to September in the hills of India.Gladiolus is very rich in its varietal wealth therefore, varietal evaluation in a particular growing condition becomes necessity of time to find out suitable variety for a particular region. Improvement of any crop is a continuous process and long process as well and, in this crop, tremendous scope is available to improve the existing cultivars, besides, other economical plants, the growth and development of gladiolus is governed by its genetic makeup and environmental factors of the growing region and various management practices. Among the various agro-techniques, the optimum planting time is of outmost importance. The Present investigation efforts aim to standard time of planting and suitability of varieties for local climate and edaphic conditions of the Nalanda (Bihar). A field investigation was conducted during winter season of 2018-19 at Research Farm of Nalanda College of Horticulture, Noorsarai, Nalanda, Bihar. Corms of gladiolus cultivars viz., Red Beauty, Candyman, White Prosperity and Intrepid were planted at different planting dates. The soils of experimental site are newly formed alluvial soils with pH 7.40. The experiment consisted of 16 treatment combinations with four (04) varieties and four planting dates (D1- 25th Sept., D2- 10th October and D3- 25th Oct. and D4-10th Nov.) were laid out in split-plot-design with three replications. Minimum days to sprouting of corm (16.33 days), number of leaves per plant (11.27), length of leaves (86.87cm.) were with D2V2. However, maximum plant height (146.07 cm.) was in D2V1. Minimum days to initiation of spike (80.47 days), days taken to open first floret (95.07 days) and maximum length of spike (126.07cm.) were observed in D2V1. On the other hand, maximum numbers of florets per spike (21.20), fresh weight of flower spike (170.25 gm.), floret diameter (11.17cm.) and vase life (14.80 days) were in D2V3. Highest values for no. of corms per plant (1.40) and no. of cormels per plant (111.53) were noticed in D2V3.  Besides, corm diameter (7.53 cm) and average weight of corm per plant (123.08 gm.) were found maximum in D2V1.
Effect of Calcination Temperature on the Structural and Catalytic Efficiency of APSR-Derived CaO for Biodiesel Production
Authors: Itabiyi Olukunle Elijah , Oloyede Christopher Tunji , Dada Ebenezer Olujimi , Akinrinade Nathaniel Abidemi , Muraina Abdullateef Bello , Jekayinfa Simeon Olatayo
Published: October 2024

This study aimed to investigate the effect of varying the calcination temperature of calcium oxide (CaO) based biocatalysts for biodiesel production from low-cost feedstock (African Periwinkle Shell Residue, APSR). The synthesized APSR-derived biocatalyst was characterized through Energy Dispersive X-ray spectroscopy (EDX), Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), and Fourier Transform Infrared spectra (FTIR). The catalytic performance was examined via catalyzed transesterification of soybean oil. The results indicate that the mass fraction of the main element (Calcium, Ca) present in the APSR, increased with temperature. Likewise, the morphological composition and percentage composition of crystalline phases (CaO, SiO2 and calcite) of the derived biocatalyst increased with the increase in calcination temperature. Catalytic testing showed that the biodegradation of triglycerides in soybean oil was able to aid the conversion of oleic acid to biodiesel. The results of this study suggest that the composition and efficiency of CaO are dependent on the calcination temperature.
Disturbance dynamo effects over low‐latitude F region: A study by network of VHF spaced receivers
Authors: Kakad B. , Surve G. , Tiwari P. , Yadav V. , Bhattacharyya A.
Published: May 2017

Generation of equatorial spread F (ESF) irregularities resulting from magnetic disturbance is known for past few decades. However, better prediction models for this phenomenon are still lacking. Magnetic storms also affects the F region plasma drifts. In this work we examined variability in (i) occurrence of such freshly generated ESF and (ii) low‐latitude F region zonal plasma drifts over Indian longitude. For this purpose simultaneous observations of amplitude scintillations on 251 MHz signal, recorded by a network of spaced receivers located at low‐latitude stations, are utilized. Observational stations are situated such that it longitudinally (latitudinally) covers an area of 5.6° (13°). Here effect of disturbance dynamo (DD) electric field at low‐latitude F region and its variability are studied for three magnetic storms occurring in 2011. These magnetic storms are having nearly similar type characteristics except their start time. We find that as time difference (i.e., ΔT) between local sunset and start of magnetic activity decreases, the DD effects seen at low‐latitude F region zonal irregularity drift around midnight becomes stronger. For a given magnetic storm the DD effect on F region zonal irregularity drifts is found to be only marginally stronger at dip equator in comparison to off‐equatorial stations. Although effect of DD on F region zonal irregularity drifts are felt simultaneously, generation of fresh ESF is variable within a smaller longitudinal belt of 5.6°. It is attributed to the presence of LSWS at the bottomside of F region, as initiation of ESF is highly likely (unlikely) in the vicinity of crest (trough) of such LSWS.
Modeling modified Circumpolar Deep Water intrusions onto the Prydz Bay continental shelf, East Antarctica
Authors: Liu Chengyan , Wang Zhaomin , Cheng Chen , Xia Ruibin , Li Bingrui , Xie Zelin
Published: May 2017

An eddy‐resolving coupled regional ocean‐sea ice‐ice shelf model is employed to locate the hot spots where modified Circumpolar Deep Water (mCDW) intrudes onto the continental shelf within Prydz Bay, and locate the paths through which mCDW is transported to the Amery Ice Shelf (AIS) calving front. Evaluation of the model output is with satellite, hydrographic and borehole data. Two critical windows responsible for mCDW intrusions are identified. The first is the eastern branch of the cyclonic Prydz Bay gyre (PBG) that carries mCDW to the ice front line, accounting for an annual mean heat transport of ∼8.7 ×1011 J s−1. The second is located to the east of the Four Ladies Bank (FLB) where mCDW is channeled through submarine troughs, accounting for an annual mean heat transport of ∼16.2 ×1011 J s−1. The eddy‐induced heat transport accounts for ∼23% in the path of the PBG and ∼52% in the path of the eastern coastal current, with respect to their total onshore heat transport. The seasonal pulsing of mCDW intrusions is greatly dependent on the seasonal cycle of the Antarctic Slope Current (ASC) that peaks with a maximum of ∼29.3 Sv at 75°E in June. In austral winter, mCDW is allowed to access the eastern flank of the AIS calving front with potential consequences for the basal mass balance of the AIS. The dynamic effects of small‐scale troughs on the longshore ASC play an important role in the onshore mCDW transport.
Hydraulics and mixing in a laterally divergent channel of a highly stratified estuary
Authors: Geyer W. Rockwell , Ralston David K. , Holleman Rusty C.
Published: May 2017

Estuarine mixing is often intensified in regions where topographic forcing leads to hydraulic transitions. Observations in the salt‐wedge estuary of the Connecticut River indicate that intense mixing occurs during the ebb tide in regions of supercritical flow that is accelerated by lateral expansion of the channel. The zones of mixing are readily identifiable based on echo‐sounding images of large‐amplitude shear instabilities. The gradient Richardson number (Ri) averaged across the mixing layer decreases to a value very close to 0.25 during most of the active mixing phase. The along‐estuary variation in internal Froude number and interface elevation are roughly consistent with a steady, inviscid, two‐layer hydraulic representation, and the fit is improved when a parameterization for interfacial stress is included. The analysis indicates that the mixing results from lateral straining of the shear layer, and that the rapid development of instabilities maintains the overall flow near the mixing threshold value of Ri = 0.25, even with continuous, active mixing. The entrainment coefficient can be estimated from salt conservation within the interfacial layer, based on the finding that the mixing maintains Ri = 0.25. This approach leads to a scaling estimate for the interfacial mixing coefficient based on the lateral spreading rate and the aspect ratio of the flow, yielding estimates of turbulent dissipation within the pycnocline that are consistent with estimates based on turbulence‐resolving measurements.
Morphological characterization of coral reefs by combining lidar and MBES data: A case study from Yuanzhi Island, South China Sea
Authors: Zhang Kai , Yang Fanlin , Zhang Hande , Su Dianpeng , Li QianQian
Published: May 2017

The correlation between seafloor morphological features and biological complexity has been identified in numerous recent studies. This research focused on the potential for accurate characterization of coral reefs based on high‐resolution bathymetry from multiple sources. A standard deviation (STD) based method for quantitatively characterizing terrain complexity was developed that includes robust estimation to correct for irregular bathymetry and a calibration for the depth‐dependent variablity of measurement noise. Airborne lidar and shipborne sonar bathymetry measurements from Yuanzhi Island, South China Sea, were merged to generate seamless high‐resolution coverage of coral bathymetry from the shoreline to deep water. The new algorithm was applied to the Yuanzhi Island surveys to generate maps of quantitive terrain complexity, which were then compared to in situ video observations of coral abundance. The terrain complexity parameter is significantly correlated with seafloor coral abundance, demonstrating the potential for accurately and efficiently mapping coral abundance through seafloor surveys, including combinations of surveys using different sensors.
Role for Atlantic inflows and sea ice loss on shifting phytoplankton blooms in the Barents Sea
Authors: Oziel L. , Neukermans G. , Ardyna M. , Lancelot C. , Tison J‐L. , Wassmann P. , Sirven J. , Ruiz‐Pino D. , Gascard J‐C.
Published: May 2017

Phytoplankton blooms in the Barents Sea are highly sensitive to seasonal and interannual changes in sea ice extent, water mass distribution, and oceanic fronts. With the ongoing increase of Atlantic Water inflows, we expect an impact on these blooms. Here, we use a state‐of‐the‐art collection of in situ hydrogeochemical data for the period 1998–2014, which includes ocean color satellite‐derived proxies for the biomass of calcifying and noncalcifying phytoplankton. Over the last 17 years, sea ice extent anomalies were evidenced having direct consequences for the spatial extent of spring blooms in the Barents Sea. In years of minimal sea ice extent, two spatially distinct blooms were clearly observed: one along the ice edge and another in ice‐free water. These blooms are thought to be triggered by different stratification mechanisms: heating of the surface layers in ice‐free waters and melting of the sea ice along the ice edge. In years of maximal sea ice extent, no such spatial delimitation was observed. The spring bloom generally ended in June when nutrients in the surface layer were depleted. This was followed by a stratified and oligotrophic summer period. A coccolithophore bloom generally developed in August, but was confined only to Atlantic Waters. In these same waters, a late summer bloom of noncalcifying algae was observed in September, triggered by enhanced mixing, which replenishes surface waters with nutrients. Altogether, the 17 year time‐series revealed a northward and eastward shift of the spring and summer phytoplankton blooms.
Sahel precipitation and regional teleconnections with the Indian Ocean
Authors: Dyer Ellen L. E. , Jones Dylan B. A. , Li Ryan , Sawaoka Hiromitsu , Mudryk Lawrence
Published: May 2017

The drought in the Sahel in the 1980s has been associated with Indian Ocean warming, although the Sahel has experienced a recovery in precipitation since the 1990s, despite continued warming in the Indian Ocean. Using the Community Earth System Model (CESM), we examined the linkages between the pattern of Indian Ocean warming and changes in atmospheric circulation over the Indian Ocean and North Africa to determine how they impact Sahel precipitation. The influence of the Indian Ocean on Sahel precipitation was investigated using a series of sea surface temperature (SST) sensitivity experiments. We identified two mechanisms by which the Indian Ocean can alter Sahel precipitation. The first mechanism is associated with perturbations in SSTs on the equator that alter Sahel precipitation by modulating the Asian monsoon circulation and driving changes in descent in North Africa. The second mechanism is associated with SST perturbations that cover more of the basin and alter the overturning circulation between the Indian and Atlantic Oceans. These two mechanisms result in different precipitation responses in the Sahel: the first induces an increase in precipitation as a result of warming in the Indian Ocean, whereas the second produces a decrease in Sahel precipitation in response to warming. Our results suggest that obtaining robust projections of precipitation in the Sahel will require reliably capturing the scale and spatial patterns of Indian Ocean warming.
Sensitivities of the hydrologic cycle to model physics, grid resolution, and ocean type in the aquaplanet Community Atmosphere Model
Authors: Benedict James J. , Medeiros Brian , Clement Amy C. , Pendergrass Angeline G.
Published: May 2017

Precipitation distributions and extremes play a fundamental role in shaping Earth's climate and yet are poorly represented in many global climate models. Here, a suite of idealized Community Atmosphere Model (CAM) aquaplanet simulations is examined to assess the aquaplanet's ability to reproduce hydroclimate statistics of real‐Earth configurations and to investigate sensitivities of precipitation distributions and extremes to model physics, horizontal grid resolution, and ocean type. Little difference in precipitation statistics is found between aquaplanets using time‐constant sea‐surface temperatures and those implementing a slab ocean model with a 50 m mixed‐layer depth. In contrast, CAM version 5.3 (CAM5.3) produces more time mean, zonally averaged precipitation than CAM version 4 (CAM4), while CAM4 generates significantly larger precipitation variance and frequencies of extremely intense precipitation events. The largest model configuration‐based precipitation sensitivities relate to choice of horizontal grid resolution in the selected range 1–2°. Refining grid resolution has significant physics‐dependent effects on tropical precipitation: for CAM4, time mean zonal mean precipitation increases along the Equator and the intertropical convergence zone (ITCZ) narrows, while for CAM5.3 precipitation decreases along the Equator and the twin branches of the ITCZ shift poleward. Increased grid resolution also reduces light precipitation frequencies and enhances extreme precipitation for both CAM4 and CAM5.3 resulting in better alignment with observational estimates. A discussion of the potential implications these hydrologic cycle sensitivities have on the interpretation of precipitation statistics in future climate projections is also presented.
How are streamflow responses to the El Nino Southern Oscillation affected by watershed characteristics?
Authors: Rice Joshua S. , Emanuel Ryan E.
Published: May 2017

Understanding the factors that influence how global climate phenomena, such as the El‐Nino Southern Oscillation (ENSO), affect streamflow behavior is an important area of research in the hydrologic sciences. While large‐scale patterns in ENSO‐streamflow relationships have been thoroughly studied, and are relatively well‐understood, information is scarce concerning factors that affect variation in ENSO responses from one watershed to another. To this end, we examined relationships between variability in ENSO activity and streamflow for 2731 watersheds across the conterminous U.S. from 1970 to 2014 using a novel approach to account for the intermediary role of precipitation. We applied an ensemble of regression techniques to describe relationships between variability in ENSO activity and streamflow as a function of watershed characteristics including: hydroclimate, topography, geomorphology, geographic location, land cover, soil characteristics, bedrock geology, and anthropogenic influences. We found that variability in watershed scale ENSO‐streamflow relationships was strongly related to factors including: precipitation timing and phase, forest cover, and interactions between watershed topography and geomorphology. These, and other influential factors, share in common the ability to affect the partitioning and movement of water within watersheds. Our results demonstrate that the conceptualization of watersheds as signal filters for hydroclimate inputs, commonly applied to short‐term rainfall‐runoff responses, also applies to long‐term hydrologic responses to sources of recurrent climate variability. These results also show that watershed processes, which are typically studied at relatively fine spatial scales, are also critical for understanding continental scale hydrologic responses to global climate.
Mars's magnetotail: Nature's current sheet laboratory
Authors: Artemyev A. V. , Angelopoulos V. , Halekas J. S. , Runov A. , Zelenyi L. M. , McFadden J. P.
Published: May 2017

The configuration and stability of an important kinetic plasma structure, the current sheet, determine the efficiency of magnetic energy storage, release, and transport in surrounding plasmas. These properties depend on β (the ratio of plasma pressures to magnetic field pressures) and Mach number M (the ratio of bulk velocities to magnetosonic velocities). For the most investigated current sheet, the near‐Earth magnetotail current sheet, these parameters fall within a relatively narrow range of values (high β, low M). To investigate current sheet behavior for a wider range of parameters, we explore current sheets in the magnetotail of Mars using Mars Atmosphere and Volatile Evolution (MAVEN) mission observations. We find that low‐β, high‐M current sheets are abundant in Mars's magnetotail, but high‐β, low‐M current sheets can also be found there. Low‐β current sheets are nearly force‐free, whereas high‐M current sheets are balanced by a plasma flow gradient along the tail. We compare current sheet distributions in a (β,M) space for the Martian magnetotail, the near‐Earth magnetotail (using Time History of Events and Macroscale Interactions during Substorms (THEMIS) mission), and the distant magnetotail (using Acceleration, Reconnection, Turbulence, and Electrodynamics of the Moon's Interaction with the Sun (ARTEMIS) mission). We also find that the pressure balance in the Martian magnetotail current sheet can occur by contributions from a wide range of ion species, or, in low beta cases, from field‐aligned currents generation of a force‐free magnetic field configuration. The Martian magnetotail is a natural laboratory where current sheet of various types can be found and investigated.
Nonlinear Landau resonance with localized wave pulses
Authors: Artemyev A. V. , Rankin R. , Vasko I. Y.
Published: May 2017

Wave‐particle resonant interaction is responsible for many important space plasma processes and can be formally described theoretically for two main regimes: particle scattering (quasilinear diffusion) by low‐intensity waves and particle trapping/phase bunching by sufficiently intense waves. There are important modifications of these regimes in inhomogeneous plasma systems. However, almost all theoretical results have been derived for harmonic waves and linear plasma modes. High‐resolution spacecraft measurements of spatially localized plasma waves in Earth's magnetosphere demonstrate electron acceleration attributed to the Landau resonance mechanism. In the classical mechanism, the magnitude of the electric potential determines the maximum energy gain of electrons. However, a less reported mechanism of electron acceleration becomes possible in inhomogeneous plasma and magnetic field. In this Commentary, we discuss how combination of wave localization and plasma inhomogeneity modifies the nonlinear Landau resonance. We underline the important property of this resonance: an electron energy gain depends on the gradient in wave potential and not just its magnitude. We also consider this modified resonance mechanism in context of generation of hot field‐aligned electron populations, particle transport, and energy transfer in the magnetosphere.
Low‐frequency electromagnetic cyclotron waves in and around magnetic clouds: STEREO observations during 2007–2013
Authors: Zhao G. Q. , Chu Y. H. , Lin P. H. , Yang Y. H. , Feng H. Q. , Wu D. J. , Liu Q.
Published: May 2017

Wave activities in the solar wind are an important topic and magnetic clouds (MCs) are a common phenomenon in interplanetary space, though waves activities associated with MCs have not been well documented. Based on a survey of 120 MCs observed by STEREO spacecraft during the years 2007–2013, this work studies electromagnetic cyclotron waves (ECWs) near the proton cyclotron frequency in and around MCs. For total 7807 ECW events, 24% of them occurred in the regions within MCs while 76% occurred in the regions around MCs. Statistics indicate that ECWs around MCs have higher frequencies, wider bandwidths, and stronger powers relative to the waves in MCs. More ECWs, on the other hand, tend to be related to a plasma with higher temperature, lower density, and larger velocity. In particular, it is found that there exist positive power law correlations between plasma betas and the wave frequencies, bandwidths, and powers. The results imply that the plasma beta should play an important role in determining the properties of ECWs, which is consistent with previous theory studies and the recent simulation results.