scholarly journals Morphological characteristics of the southwest deep - depression East Sea region

2021 ◽  
Vol 62 (4) ◽  
pp. 29-37
Author(s):  
Bat Van Dang ◽  
Chi Kim Thi Ngo ◽  
Binh Van Phan ◽  
Hiep Huu Nguyen ◽  
Hau Vinh Bui ◽  
...  
Keyword(s):  
Morphological Characteristics ◽  
Field Investigation ◽  
Horizontal Surface ◽  
East Sea ◽  
Mountain Range ◽  
Slope Surface ◽  
The North ◽  
Different Depths ◽  
Depression Surface ◽  
Inclined Surface

Morphological characteristics of the southwestern deep-depression East Sea have been defined based on the subdivision into co-origin surfaces. The results show that, the study area has 16 morphological units, including: Horizontal surface, slightly inclined surface, continental shelf accumulation, 200÷300 m depth; The surface is slightly inclined and wavy accumulates the outer shelf, 300÷700 m deep; Horizontal surface, abrasive, 500÷700 m (Guyot); Abrasive horizontal surface (Guyot), depth 1,300÷1,600 m; Abrasive horizontal surface (Guyot), depth -2,000 m; The surface of the ancient volcanic crest is distributed at different depths; Young volcanic surface, 1,200÷3,000 m deep; Wavy, accumulative plain, continental rise, 1,100÷1,800 m deep; Plain transport - accumulation plain, depth 1,100÷2,300 m; The smooth plain transports accumulates, depth 2,300÷3,000 m; The plain is divided by underground hills and mountains in the north, 2,000÷2,600 m deep; The plain is strongly dissected of underground mountains, 1,700÷2,600 m deep; Deep depression surface splits; Tectonic slope surface, continental slope 800÷1,400 m depth; Slope surface of the Northwestern underground mountain range 1,800÷2,600 m; Slope surface of the Southeastern underground mountain range 2000÷2900 m. Based on the morphological characteristics of the study area, field investigation, and analytical results allowed us to capture the potential areas of the Fe - Mn nodule and crust, namely: morphological units such as Guyot, young volcanic surface are supposed to be the prospect of the Fe - Mn crust while the deepwater surfaces demonstrate favorable place for Fe - Mn nodule can produce accumulation.

Paris nitida (Melanthiaceae): revisting morphological characteristics, biogeography and phylogenetic relationships

Phytotaxa ◽  
2019 ◽  
Vol 424 (3) ◽  
pp. 184-190
Author(s):  
WEN-XIA RAO ◽  
HONG-XIANG YIN ◽  
RU-YU YAO
Keyword(s):  
Morphological Characteristics ◽  
Field Investigation ◽  
Morphological Observation ◽  
Literature Study ◽  
The North ◽  
Nj Tree ◽  
Nrits Sequence ◽  
Guizhou Plateau ◽  
Distribution Record ◽  
New Distribution

Paris nitida is a newly published species, but little is known about its morphological characteristics, distribution and phylogenetic relationship. In this study, field investigation, literature study, morphological observation and molecular nrITS sequence analysis were used to improve knowledge of this species. Morphological traits of P. nitida were found to be more similar to those of Paris fargesii var. brevipetalata, rather than Paris caobangensis as reported before; moreover, a new distribution record in the centre of the Yunnan-Guizhou Plateau was found; additionally, P. nitida was clustered with Paris fargesii var. fargesii, P. fargesii var. brevipetalata, and P. caobangensi in a NJ tree based on the ITS sequences. Accordingly, P. nitida is more closely related to P. sect. Fargesianae rather than P. caobangensis; the habitat of P. nitida is located from south of the Yangtze River to the north of the Nanling Mountains, mainly including the central part of Yunnan-Guizhou Plateau and central Chinese mountains. It is geographically isolated from P. caobangensis, which occurs in northern Vietnam. The central part of Yunnan-Guizhou Plateau may be its area of origin.

SEM and TEM observations of sperm development in the testis of the freshwater fish Oreochromis mossambicus

1990 ◽  
Vol 48 (3) ◽  
pp. 58-59
Author(s):  
Daryl A. Cornish ◽  
George L. Smit
Keyword(s):  
Morphological Characteristics ◽  
Oreochromis Mossambicus ◽  
Breeding Cycle ◽  
Limited Information ◽  
North West ◽  
The North ◽  
Sem And Tem ◽  
Sperm Development ◽  
Ultrastructural Characteristics ◽  
The University

Oreochromis mossambicus is currently receiving much attention as a candidater species for aquaculture programs within Southern Africa. This has stimulated interest in its breeding cycle as well as the morphological characteristics of the gonads. Limited information is available on SEM and TEM observations of the male gonads. It is known that the testis of O. mossambicus is a paired, intra-abdominal structure of the lobular type, although further details of its characteristics are not known. Current investigations have shown that spermatids reach full maturity some two months after the female becomes gravid. Throughout the year, the testes contain spermatids at various stages of development although spermiogenesis appears to be maximal during November when spawning occurs. This paper describes the morphological and ultrastructural characteristics of the testes and spermatids.Specimens of this fish were collected at Syferkuil Dam, 8 km north- west of the University of the North over a twelve month period, sacrificed and the testes excised.

scholarly journals Suspended sediment distribution under varied currents in the largest river-connected lake of China

2017 ◽  
Vol 18 (3) ◽  
pp. 994-1004 ◽  
Author(s):  
Hua Wang ◽  
Yijun Zhao ◽  
Fengnian Zhou ◽  
Huaiyu Yan ◽  
Yanqing Deng ◽  
...  
Keyword(s):  
Flow Pattern ◽  
Suspended Sediment ◽  
Flow Patterns ◽  
Field Investigation ◽  
Gravity Flow ◽  
Shear Stresses ◽  
Sediment Distribution ◽  
Back Flow ◽  
The North ◽  
Dry Seasons

Abstract Poyang Lake was selected as the research area. Based on laboratory experiment, field investigation and numerical simulation, the spatial distributions of suspended sediment (SS) under the gravity-flow, jacking-flow and back-flow patterns were quantitatively analysed. An annular flume experiment was conducted to determine the critical starting shear stresses of the sediments in the flood and dry seasons. By numerical experiment, the SS transport under different flow patterns was explored. Several results stand out. (1) The critical starting shear stresses of the sediments in the flood and dry seasons were 0.35 N·m−2 and 0.29 N·m−2, respectively. (2) Due to the strongest flow disturbance and scouring effect, SS under the gravity-flow pattern was characterized by the highest loads. The lowest SS was observed during the jacking-flow pattern, which could be attributed to the lowest water level gap between the lake and external rivers. The loads ranged from 0.053 kg·m−3 to 0.068 kg·m−3. (3) Under the back-flow pattern, SS in the north lake was evidently influenced by the Yangtze River, and the mean value was approximately 0.12 kg·m−3. With the gradually weakened back-flow impact, the SS load was decreased from the north to the middle of the lake.

scholarly journals Vegetation of the classes Hydrochari-Lemnetea Oberd. 1967 and Potametea Tx. et Prsg. 1942 in the Jegricka watercourse (The province of Vojvodina, Serbia)

2010 ◽  
pp. 99-106 ◽  
Author(s):  
Dejana Dzigurski ◽  
Slobodanka Stojanovic ◽  
Aleksa Knezevic ◽  
Ljiljana Nikolic ◽  
Branka Ljevnaic-Masic
Keyword(s):  
The Black Sea ◽  
Lower Section ◽  
Vegetation Diversity ◽  
The North ◽  
Abrupt Changes ◽  
The North Sea ◽  
Main Canal ◽  
Canal Network ◽  
Different Depths ◽  
The Individual

The Jegricka, once a natural watercourse traversing the southwestern part of the Backa region, has been turned into a canal, which became part of the main canal network of the hydro-system Danube-Tisza-Danube (Hs DTD). In its turn, the Hs DTD is part of the European waterway linking the North Sea to the Black Sea, i.e., part of the navigable Rhine-Main-Danube Canal. The watercourse is 65.4 km long and it is divided into three levels. The presence of the regulated and the nonregulated sections of the canal, frequent and abrupt changes in water level in the individual sections, different depths and surface water widths of the various sections and the fishpond constructed in the lower section cause considerable vegetation diversity. The vegetation comprises aquatic associations of the classes Hydrochari-Lemnetea Oberd. 1967 and Potametea Tx. et Prsg. 1942. The class Hydrochari-Lemnetea Oberd. 1967 includes the following phytocoenoses: Salvinio-Spirodeletum polyrrhizae Slavnic 1956, Ceratophylletum demersi (So? 27) Hild. 1956, Lemno-Utricularietum vulgaris So? 1928 and Hydrocharidetum morsus-ranae Van Langendonck 1935. The class Potametea Tx. et Prsg. 1942 includes the associations Myriophyllo-Potametum So? 1934, Najadetum marine Fukarek 1961, Nymphaeetum albae Vollmar 1947, Nymphoidetum peltate (Allorge 1922) Oberd. et M?ller 1960 and Trapetum natantis M?ller et G?rs 1960.

Trends and Variability of North American Cool-Season Extratropical Cyclones: 1979–2019

2021 ◽  
Author(s):  
Robert Fritzen ◽  
Victoria Lang ◽  
Vittorio A. Gensini
Keyword(s):  
North American ◽  
Research Question ◽  
Weather Conditions ◽  
Extratropical Cyclones ◽  
Mountain Range ◽  
Cool Season ◽  
The North ◽  
Primary Driver ◽  
Regional Reanalysis ◽  
Log Linear

AbstractExtratropical cyclones are the primary driver of sensible weather conditions across the mid-latitudes of North America, often generating various types of precipitation, gusty non-convective winds, and severe convective storms throughout portions of the annual cycle. Given ongoing modifications of the zonal atmospheric thermal gradient due to anthropogenic forcing, analyzing the historical characteristics of these systems presents an important research question. Using the North American Regional Reanalysis, boreal cool-season (October–April) extratropical cyclones for the period 1979–2019 were identified, tracked, and classified based on their genesis location. Additionally, bomb cyclones—extratropical cyclones that recorded a latitude normalized pressure fall of 24 hPa in 24-hr—were identified and stratified for additional analysis. Cyclone lifespan across the domain exhibits a log-linear relationship, with 99% of all cyclones tracked lasting less than 8 days. On average, ≈ 270 cyclones were tracked across the analysis domain per year, with an average of ≈ 18 year−1 being classified as bomb cyclones. The average number of cyclones in the analysis domain has decreased in the last 20 years from 290 year−1 during the period 1979–1999 to 250 year−1 during the period 2000–2019. Spatially, decreasing trends in the frequency of cyclone track counts were noted across a majority of the analysis domain, with the most significant decreases found in Canada’s Northwest Territories, Colorado, and east of the Graah mountain range. No significant interannual or spatial trends were noted with bomb cyclone frequency.

The Invasion of Plague in Early Modern Italy

2019 ◽  
pp. 23-50
Author(s):  
John Henderson
Keyword(s):  
Early Modern ◽  
Preventive Measures ◽  
Northern Italy ◽  
Reggio Emilia ◽  
Health Board ◽  
Mountain Range ◽  
Physical Barrier ◽  
The North ◽  
Early Modern Italy ◽  
The Dead

This chapter discusses the origins and spread of plague in northern Italy. Plague arrived in Italy in 1629 with French and German troops. It is no accident that the initial cases of plague identified in October of 1629 were first in Piedmont in the Val di Susa, west of Turin and near the border with France, and secondly in the Valtellina in Lombardy, subsequently travelling to Lake Como to the north of Milan. Other cities in northern Italy soon became infected and on May 6, 1630, the authorities as far south as Bologna announced the official outbreak of plague. Judging by the rapidity with which plague spread between these northern urban centres, one would have expected the epidemic to have arrived in Tuscany by early May, given that Bologna is only 65 miles north of Florence, but it was delayed by both natural and man-made factors. Tuscany is separated from Reggio-Emilia by the Apennine mountain range, which provided a physical barrier and facilitated the control of traffic coming from the north. The chapter then traces the preventive measures adopted by the health board as the plague approached Tuscany, including cordons sanitaires along frontiers, the removal of the sick to quarantine centres, and the rapid burial of the dead.

scholarly journals Glacial debris cover and melt water production for glaciers in the Altay, Russia

2011 ◽  
Vol 5 (1) ◽  
pp. 401-430 ◽  
Author(s):  
C. Mayer ◽  
A. Lambrecht ◽  
W. Hagg ◽  
Y. Narozhny
Keyword(s):  
Ice Melt ◽  
The North ◽  
Altay Mountains ◽  
Digital Elevation ◽  
Glacier Runoff ◽  
Debris Cover ◽  
Continuous Mass ◽  
Different Depths ◽  
The 1960S ◽  
Elevation Model

Abstract. Glaciers are important water storages on a seasonal and long-term time scale. Where high mountains are surrounded by arid lowlands, glacier runoff is an important source of water during the growing season. This situation can be found in the Altay mountains in Southern Siberia, where the recent glacierization of >700 km2 is subject to continuous mass loss, even though the shrinking is comparably slow. The glacier retreat is accompanied by an extension of supra-glacial moraine, which itself strongly influences ablation rates. To quantify these effects, the spatial evolution of debris cover since 1952 was analysed for three glaciers in the North Chuya Ridge using satellite and airborne imagery. In summer 2007, an ablation experiment was carried out on debris covered parts of Maliy Aktru glacier. Thermistors in different depths within the moraine provided data to calculate thermal resistance of the debris. A set of ablation stakes was installed at locations with differing debris thickness and observed regularly throughout the entire melt season. Air temperature from an AWS was used to calculate degree day factors in dependence of the debris thickness. To take into account the shading effect of surrounding walls and peaks, the potential solar radiation and its evolution throughout the summer was determined from a digital elevation model. This allows us to extrapolate our measurements from Maliy Aktru to the other two glaciers of the Aktru basin and to estimate basin melt rates. In addition accumulated ice melt was derived for 12 glaciers in the North Chuya Range. Changes in summer runoff from the 1960s are compared to the results from our melt model and the evolution of debris cover is analysed in respect to the melt activity.

scholarly journals Passive imaging of collisional orogens: a review of a decade of geophysical studies in the Pyrénées

2022 ◽  
Vol 193 ◽  
pp. 1
Author(s):  
Sébastien Chevrot ◽  
Matthieu Sylvander ◽  
Antonio Villaseñor ◽  
Jordi Díaz ◽  
Laurent Stehly ◽  
...  
Keyword(s):  
Imaging Techniques ◽  
Mountain Range ◽  
Seismic Signals ◽  
Passive Imaging ◽  
Tomographic Images ◽  
Bouguer Anomalies ◽  
The North ◽  
Eastern Pyrenees ◽  
Collisional Orogens ◽  
Central Pyrenees

This contribution reviews the challenges of imaging collisional orogens, focusing on the example of the Pyrenean domain. Indeed, important progresses have been accomplished regarding our understanding of the architecture of this mountain range over the last decades, thanks to the development of innovative passive imaging techniques, relying on a more thorough exploitation of the information in seismic signals, as well as new seismic acquisitions. New tomographic images provide evidence for continental subduction of Iberian crust beneath the western and central Pyrénées, but not beneath the eastern Pyrénées. Relics of a Cretaceous hyper-extended and segmented rift are found within the North Pyrenean Zone, where the imaged crust is thinner (10–25 km). This zone of thinned crust coincides with a band of positive Bouguer anomalies that is absent in the Eastern Pyrénées. Overall, the new tomographic images provide further support to the idea that the Pyrénées result from the inversion of hyperextended segmented rift systems.

scholarly journals LIDAR AND PHOTOGRAMMETRY APPROACHES FOR MONITORING LAND SURFACE MORPHOLOGY IN EPHEMERAL GULLY SYSTEM

2019 ◽  
Vol XLII-4/W18 ◽  
pp. 1065-1069
Author(s):  
X. Xu ◽  
Q. Tang
Keyword(s):  
Surface Morphology ◽  
Land Surface ◽  
Rainy Season ◽  
Field Investigation ◽  
Slope Gradient ◽  
Slope Surface ◽  
Ephemeral Gully ◽  
Topographic Characteristics ◽  
Tillage Erosion

Abstract. LIDAR and photogrammetry techniques were used to quantify the land surface morphology dynamics of ephemeral gully system based on the field investigation. LIDAR monitoring results showed that ephemeral gully occurred in the same location on the slope surface after every rainy season in the ephemeral gully system, then lateral topsoil was tilled and brought into the ephemeral gully channel, inducing 2 cm decrease around channel before rainy season of next year, which make it a cycle of erosion-tillage-erosion. During this process, imbricated landform was formed in ephemeral gully system. The photogrammetry monitoring results showed that most drop-sills distances in ephemeral gully channel were in 10 to 25 cm, while slope gradients were among 15° to 40°. The drop-sills distance and slope gradient showed negative exponent relationship. The results of this study showed that LIDAR technology can quickly acquire the topographic characteristics of the whole ephemeral gully system, while photogrammetry method could quickly acquire detailed morphology in ephemeral gully channel.

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