scholarly journals The Levantine jellyfish Rhopilema nomadica and Rhizostoma pulmo swim faster against the flow than with the flow

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Dror Malul ◽  
Tamar Lotan ◽  
Yizhaq Makovsky ◽  
Roi Holzman ◽  
Uri Shavit
Keyword(s):  
Swimming Speed ◽  
Laboratory Testing ◽  
Eastern Mediterranean ◽  
Abundant Species ◽  
Water Velocity ◽  
Pulsation Frequency ◽  
The Past ◽  
Sensory Ability

AbstractJellyfish locomotion and orientation have been studied in the past both in the laboratory, testing mostly small jellyfish, and in the field, where it was impossible to control the seawater currents. Utilizing an outdoor water flume, we tested the locomotion of jellyfish when swimming against and with currents of up to 4.5 cm s−1. We used adult jellyfish from two of the most abundant species in the eastern Mediterranean, Rhopilema nomadica and Rhizostoma pulmo, and measured their pulsation frequency and swimming speed relative to the water. While pulsation frequency was not affected by the water velocity, jellyfish swam faster against the current than with it. This finding suggests that jellyfish possess a sensory ability, whose mechanism is currently unknown, enabling them to gauge the flow and react to it, possibly in order to reduce the risk of stranding.

Land-sea correlations in the Eastern Mediterranean region over the past c. 800 kyr based on macro- and cryptotephras from ODP Site 964 (Ionian Basin)

2021 ◽  
Vol 255 ◽  
pp. 106811
Author(s):  
Polina Vakhrameeva ◽  
Andreas Koutsodendris ◽  
Sabine Wulf ◽  
Maxim Portnyagin ◽  
Oona Appelt ◽  
...  
Keyword(s):  
Mediterranean Region ◽  
Eastern Mediterranean ◽  
Eastern Mediterranean Region ◽  
The Past

scholarly journals New Book Chronicle

Antiquity ◽  
2017 ◽  
Vol 91 (359) ◽  
pp. 1401-1411
Author(s):  
Robert Witcher
Keyword(s):  
Material Culture ◽  
North Africa ◽  
Eastern Mediterranean ◽  
Trade Agreements ◽  
Technology Change ◽  
Belt And Road Initiative ◽  
The Past ◽  
Transfer Of Technology ◽  
Belt And Road ◽  
New Phase

Is the era of globalisation on the wane or on the cusp of a new phase of extraordinary expansion? US president Trump's abandonment of trade agreements and the rise of protectionism coincide with China's ‘Belt and Road Initiative’, an unprecedented investment in infrastructure across Asia, Europe and North Africa to improve the connectivity of China with its markets by both land and sea. The future is therefore anyone's guess, but what about the past? There has been much discussion by archaeologists about ancient globalisations (most recently, Hodos 2017), but archaeological studies have often typically been set within the looser framework of ‘connectivity’—the interconnectedness of people and places and the movement of material culture and ideas. The books reviewed here are concerned with various aspects of connectivity, focusing on the Eastern Mediterranean and its European hinterland. All of the volumes are edited collections, each adopting a different unifying theme—the influence of Braudel, a single country as microcosm, the transfer of technology, changevstradition, and the effects of boundaries and frontiers. Do any wider insights into connectivity in the past emerge? And where might archaeological studies of connectivity go next?

Climate and environmental context of the Mongol invasion of Syria and defeat at ‘Ayn Jālūt (1258–1260 CE)

Erdkunde ◽  
2021 ◽  
Vol 75 (2) ◽  
pp. 87-104
Author(s):  
Nicola Di Cosmo ◽  
Sebastian Wagner ◽  
Ulf Büntgen
Keyword(s):  
Strategic Alliances ◽  
Turning Point ◽  
Environmental Changes ◽  
Environmental Variability ◽  
State Of The Art ◽  
Eastern Mediterranean ◽  
The Caucasus ◽  
Mountainous Regions ◽  
The Past ◽  
Climate Reconstructions

After a successful conquest of large parts of Syria in 1258 and 1259 CE, the Mongol army lost the battle of 'Ayn Jālūt against Mamluks on September 3, 1260 CE. Recognized as a turning point in world history, their sudden defeat triggered the reconfiguration of strategic alliances and geopolitical power not only in the Middle East, but also across much of Eurasia. Despite decades of research, scholars have not yet reached consensus over the causes of the Mongol reverse. Here, we revisit previous arguments in light of climate and environmental changes in the aftermath of one the largest volcanic forcings in the past 2500 years, the Samalas eruption ~1257 CE. Regional tree ring-based climate reconstructions and state-of-the-art Earth System Model simulations reveal cooler and wetter conditions from spring 1258 to autumn 1259 CE for the eastern Mediterranean/Arabian region. We therefore hypothesize that the post-Samalas climate anomaly and associated environmental variability affected an estimated 120,000 Mongol soldiers and up to half a million of their horses during the conquest. More specifically, we argue that colder and wetter climates in 1258 and 1259 CE, while complicating and slowing the campaign in certain areas, such as the mountainous regions in the Caucasus and Anatolia, also facilitated the assault on Syria between January and March 1260. A return to warmer and dryer conditions in the summer of 1260 CE, however, likely reduced the regional carrying capacity and may therefore have forced a mass withdrawal of the Mongols from the region that contributed to the Mamluks’ victory. In pointing to a distinct environmental dependency of the Mongols, we offer a new explanation of their defeat at 'Ayn Jālūt, which effectively halted the further expansion of the largest ever land-based empire.

Swimming speed estimation of extinct marine reptiles: energetic approach revisited

Paleobiology ◽  
2002 ◽  
Vol 28 (2) ◽  
pp. 251-262 ◽  
Author(s):  
Ryosuke Motani
Keyword(s):  
Mathematical Model ◽  
Metabolic Rate ◽  
Swimming Speed ◽  
Body Shape ◽  
Speed Estimation ◽  
The Past ◽  
Marine Reptiles ◽  
Energetic Approach ◽  
Shape Models ◽  
Significant Tendency

Cruising speeds of Mesozoic marine reptiles have been estimated in the past by using a mathematical model of energetic equilibrium during steady swimming. This method suffered from a significant tendency to overestimate speeds of extant cetaceans for no clear reason, which raised questions about the validity of the approach itself. The present study identifies the factors that caused this shortcoming and proposes corrections and some additional modifications. These include the use of more accurate body shape models, updated metabolic rate models, and optimal rather than critical swimming speeds. The amended method successfully approximates published optimal speeds of several extant marine vertebrates, including cetaceans, showing that the basic framework of the energetic approach is valid. With this confirmation, the method was applied to Mesozoic marine reptiles, by assuming three different metabolic rate categories known in extant swimming vertebrates (i.e., average ectothermic, raised ectothermic, and marine endothermic levels). The results support previous inferences about the relative cruising capabilities of Mesozoic marine reptiles (i.e., ichthyosaurs > plesiosaurs > mosasaurs). Stenopterygius, a thunniform ichthyosaur, was probably capable of cruising at a speed at least comparable to those reported for some extant thunniform teleosts with similar diets (~1 m/second).

The Medina Wrench: a key to the kinematics of the central and eastern Mediterranean over the past 5 Ma

1987 ◽  
Vol 82 (1-2) ◽  
pp. 87-106 ◽  
Author(s):  
D. Jongsma ◽  
J.M. Woodside ◽  
G.C.P. King ◽  
J.E. van Hinte
Keyword(s):  
Eastern Mediterranean ◽  
The Past

Rethinking of Turkey’s Geopolitics together with Eastern Mediterranean. Turkish Perspective

2021 ◽  
Vol 705 (2) ◽  
pp. 45-66
Author(s):  
Arıboğan Deniz Ülke ◽  
Ibrahim Arslan
Keyword(s):  
Middle East ◽  
Raw Materials ◽  
Eastern Mediterranean ◽  
International System ◽  
The United States ◽  
The Past ◽  
Humanitarian Interventions ◽  
The Us ◽  
Transportation Accessibility ◽  
The Eu

In the studies carried out within the scope of geopolitical discipline, the expression "geography is destiny" is frequently used and it is claimed that geography has unchangeable, irreversible qualities and the policies implemented are shaped through this assumption. This assumption ignores the humanitarian interventions over the geography and makes it difficult to understand the results produced by these interventions at both regional and global level. Similarly, the dynamic nature of international relations reveals new actors in the international system in times of bounce and collapse, and the borders that expand or narrow with each transformation can differentiate the geopolitical view with new sovereign countries. In the historical process, transportation accessibility, trade, search for raw materials, security and alliance relations have caused the same geography to be interpreted differently in different periods. This situation also applies to the geography of Turkey had been the homeland of empires. The developments in the Middle East over the past two decades has created a sensitivity in the relations between Turkey and the West, especially the United States. Competing interests with the EU and the US in the Middle East and the Eastern Mediterranean, has necessitated a reassessment of Turkey's geography.

Lessons Learned From Freespans at Pipeline Watercourse Crossings

2020 ◽  
Author(s):  
Gerry Ferris
Keyword(s):  
Static Load ◽  
Water Velocity ◽  
Lessons Learned ◽  
Vortex Induced Vibration ◽  
Water Loading ◽  
Relevant Question ◽  
The Past ◽  
Load Limit ◽  
Pipeline Failure

Abstract Over the past 10 years inspections (site visits, boat based surveys or diver surveys) have been completed at nearly 20,000 pipeline watercourse crossings for 20 different pipeline owners. During the last 10 years there have been 721 unique locations where an exposed pipeline was found and at 213 of these locations a freespan was encountered. Only one of the freespans resulted in the failure (loss of product) of the pipeline. This record illustrates what is now become widely accepted, that pipeline exposure does not necessarily lead to pipeline failure. The record adds to this, pipeline freespan does not necessarily lead to failure. This highlights that the relevant question for “water loading caused pipeline failure” is: Does the combination of freespan length and water velocity exceed a combination that would lead to vortex induced vibration or the exceedance of the static load limit of the pipe?

Exoskeletons

2019 ◽  
pp. 234-259
Author(s):  
Priyanshu Agarwal ◽  
Ashish D. Deshpande
Keyword(s):  
Case Studies ◽  
Energy Efficient ◽  
Laboratory Testing ◽  
Human Performance ◽  
State Of The Art ◽  
Upper Body ◽  
The Past ◽  
The Future ◽  
Human Use ◽  
Exoskeleton Design

The past few decades have witnessed a rapid explosion in research surrounding robotic exoskeletons due to their promising applications in medicine and human performance augmentation. Several advances in technology have led to the development of more energy efficient and viable prototypes of these devices. However, despite this rapid advancement in exoskeleton technology, most of the developed devices are limited to laboratory testing and a very few of them are commercially available for human use. This chapter discusses the advances in various constituting technologies including actuation, sensing, materials, and controls that made exoskeleton research feasible. Also presented are case studies on two state-of-the-art robotic exoskeletons, Harmony and Maestro, developed for rehabilitation of the upper body. The chapter concludes with a discussion on the ongoing challenges in exoskeleton design and ethical, social, and legal considerations related to the use of these devices and the future of exoskeletons.

A first preliminary study of the shallow water sponge fauna from Cyprus Island (Eastern Mediterranean)

Zootaxa ◽  
2018 ◽  
Vol 4450 (5) ◽  
pp. 594
Author(s):  
COSTA GABRIELE ◽  
GIUSSANI VALENTINA ◽  
KLETOU DEMETRIS ◽  
KLEITOU PERIKLIS ◽  
PANSINI MAURIZIO ◽  
...  
Keyword(s):  
Shallow Water ◽  
Mediterranean Sea ◽  
Eastern Mediterranean ◽  
Sponge Species ◽  
Commercial Importance ◽  
The Past ◽  
Number Of Species ◽  
Mediterranean Areas ◽  
The World ◽  
Preliminary Study

Currently, more than 8,500 valid sponge species are reported in the World Porifera Database (http://www.marinespecies.org/porifera/) (van Soest et al. 2018). The Mediterranean Sea sponge fauna, counting almost 700 species, is one of the best documented in the world (Pronzato 2003; Pansini et al. 2011; van Soest et al. 2018) but the eastern part of the basin is by far less studied, in comparison with other Mediterranean areas (Pansini et al. 2000; Voultsiadou & Vafidis 2004; Topaloğlu & Evcen 2014). A small number of species, mainly belonging to the cosmopolitan genus Spongia (Dictyoceratida), are commonly used as bath sponges. Aim of this work is to provide further information on Cyprus Island sponges in general and on species that had commercial importance in the past. 

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