Catalogue Search | MBRL
Are you sure you want to remove the book from the shelf?
{{itemTitle}}
620
result(s) for
"Stock, Michael"
Sort by:
The flying zoo : birds, parasites, and the world they share
\"An enthusiastic zoological tribute to birds and the parasites that live in and on them is revealed in Michael Stock's exposé, The Flying Zoo. From the Crozet Archipelago and the Galapagos Islands to our backyards, parasites--fleas, lice, ticks, flukes--live in both sinister and symbiotic interdependency with host birds. Written with a scientist's exuberance of the beauty of pattern in nature, a co-evolutionary dance unfolds among an astounding cast of creatures living in a complex and paradoxical co-habitation. It is the contemporary follow-up to the classic Fleas, Flukes & Cuckoos. Students of biology, their instructors, and birders alike will want this volume on their shelves, as will natural history readers looking for a new tale of tails.\"-- Provided by publisher.
Book
Upgrades of the Earth Networks Total Lightning Network in 2021
The Earth Networks Total Lightning Network (ENTLN) launched a new processor (P2021) in December 2021. Some major upgrades were made in the new processor, including a new classification algorithm, a new propagation model, and regional data processing architecture. Ground-truth datasets of natural and rocket-triggered lightning acquired in Florida were used to evaluate the performance characteristics of the new processor. Compared to the last processor launched in 2015 (P2015), the stroke classification accuracy increased from 91% to 94% for natural lightning and from 86% to 88% for rocket-triggered lightning. The location accuracy improved significantly with the median location error decreasing from 215 m to 92 m. On a global scale, we found the number of pulses detected by the ENLTN increased in all regions with an overall detection gain of 149%. One can see modest gains in detection in regions with a fairly dense network of sensors and significant gains in regions where sensor density is much lower. Each of the major upgrades as well as their influences on the performance characteristics of the ENLTN are discussed.
Journal Article
كيف تعمل البورصة : دليل المستثمر الصغير
في أوقات تقلب أسعار الأسهم وحدوث تغيرات في نظام التجارة، يحتاج المستثمر لمعرفة معلومات كثيرة عن سوق البورصة حتى يمكنه طرح الأسئلة المناسبة وعمل الاختيارات الصحيحة وحتى لا ينخدع بمعسول الكلام الذي يتشدق به أيٍ من مندوبي المبيعات. ستوضح هذه النسخة الجديدة المنقحة للمستثمرين ما يتم بيعه وشرائه وكيفية القيام القيام بذلك ومن يقوم به ومع من ولمن وكيفية تقييم الأسهم. وبأسلوبه الواضح السلس، يقتحم \"مايكل بيكيت\" عالم الاستثمار ليجيب عن مثل هذه الاستفسارات : ما تعريف الأسهم ؟ ما تعريف الأوراق المالية المضمونة ؟ ما تعريف عقود الخيارات والعقود الآجلة ؟ ما تعريف الأسهم الأجنبية ؟ كيف تنتقي السهم الذي ستقوم بشرائه ؟ من تثق بنصيحته ؟ متى تبيع سهما؟ في الواقع، تعد المضاربة فى البورصة فرصة ذهبية لجني أماول طائلة، والأمر ليس محتاجاً إلى عبثرية، ولكنه يحتاج إلى يقظة وذكاء وقدر بير من التوفيق، ويحتاج كذكلك إلى تلك النصائح والتليحات الواعية التى يتضمنها هذا الكتاب بين طياته.
BOOK
Magma chambers versus mush zones: constraining the architecture of sub-volcanic plumbing systems from microstructural analysis of crystalline enclaves
There are clear microstructural differences between mafic plutonic rocks that formed in a dynamic liquid-rich environment, in which crystals can be moved and re-arranged by magmatic currents, and those in which crystal nucleation and growth are essentially in situ and static. Crystalline enclaves, derived from deep crustal mushy zones and erupted in many volcanic settings, afford a unique opportunity to use the understanding of microstructural development, established from the study of intrusive plutons, to place constraints on the architecture of sub-volcanic systems. Here, we review the relevant microstructural literature, before applying these techniques to interrogate the crystallization environments of enclaves from the Kameni Islands of Santorini and Rábida Volcano in the Galápagos. Crystals in samples of deep-sourced material from both case studies preserve evidence of at least some time spent in a liquid-rich environment. The Kameni enclaves appear to record an early stage of crystallization during which crystals were free to move, with the bulk of crystallization occurring in a static, mushy environment. By contrast, the Rábida enclaves were sourced from an environment in which hydrodynamic sorting and re-arrangement by magmatic currents were common, consistent with a liquid-rich magma chamber. While presently active volcanoes are thought to be underlain by extensive regions rich in crystal mush, these examples preserve robust evidence for the presence of liquid-rich magma chambers in the geological record. This article is part of the Theo Murphy meeting issue ‘Magma reservoir architecture and dynamics'.
Journal Article
Observations of narrow bipolar events reveal how lightning is initiated in thunderstorms
A long-standing but fundamental question in lightning studies concerns how lightning is initiated inside storms, given the absence of physical conductors. The issue has revolved around the question of whether the discharges are initiated solely by conventional dielectric breakdown or involve relativistic runaway electron processes. Here we report observations of a relatively unknown type of discharge, called fast positive breakdown, that is the cause of high-power discharges known as narrow bipolar events. The breakdown is found to have a wide range of strengths and is the initiating event of numerous lightning discharges. It appears to be purely dielectric in nature and to consist of a system of positive streamers in a locally intense electric field region. It initiates negative breakdown at the starting location of the streamers, which leads to the ensuing flash. The observations show that many or possibly all lightning flashes are initiated by fast positive breakdown.
How lightning is initiated inside storms has been a long-standing and fundamental question. Here, the authors report observations of a previously unrecognized type of discharge, called fast positive breakdown, that is found to initiate many and potentially all lightning discharges in storms.
Journal Article
Fast negative breakdown in thunderstorms
Thunderstorms are natural laboratories for studying electrical discharges in air, where the vast temporal, spatial, and energy scales available can spawn surprising phenomena that reveal deficiencies in our understanding of dielectric breakdown. Recent discoveries, such as sprites, jets, terrestrial gamma ray flashes, and fast positive breakdown, highlight the diversity of complex phenomena that thunderstorms can produce, and point to the possibility for electrical breakdown/discharge mechanisms beyond dielectric breakdown theory based mainly on laboratory experiments. Here we present one such confounding discovery, termed fast negative breakdown, that does not fit with our current understanding of dielectric breakdown. Our adaptation of radio astronomy imaging techniques to study extremely transient lightning-associated events confirms that electrical breakdown in thunderstorms can begin with oppositely-directed fast breakdown of negative polarity, similar and in addition to fast positive breakdown expected from conventional dielectric theory and recent observations. The discovery of fast negative breakdown calls for an addendum to the physical description of electrical discharges in air.
Recent studies have shown that lightning is initiated by a newly-recognized discharge process called fast positive breakdown. Here, the authors present observational evidence of fast breakdown but of negative polarity, seemingly contrary to current understanding of discharge physics.
Journal Article
Late-stage volatile saturation as a potential trigger for explosive volcanic eruptions
Magma reservoirs are thought to grow relatively slowly, assembling incrementally under volatile-saturated conditions. Eruptions may be triggered by injections of volatile-rich melt, or generation of over-pressure due to protracted crystallization. Here, we analyse fluorine, chlorine and water in apatite crystals trapped at different stages of magma evolution, and in melt inclusions from clinopyroxene and biotite crystals expelled during an explosive eruption of the Campi Flegrei caldera, Italy, about 4,000 years ago. We combine our geochemical analyses with thermodynamic modelling to reconstruct the evolution of magmatic volatile contents leading up to the explosive eruption. We find that the magma reservoir remained persistently water-undersaturated throughout most of its lifetime. Even crystals in contact with the melt shortly before eruption show that the magma was volatile-undersaturated. Our models suggest that the melt reached volatile saturation at low temperatures, just before eruption. We suggest that late-stage volatile saturation probably triggered the eruption, and conclude that ‘priming’ of the magma system for eruption may occur on timescales much shorter than the decadal to centennial timescales thought typical for magma reservoir assembly. Thus, surface deformation pulses that record magma assembly at depth beneath Campi Flegrei and other similar magmatic systems may not be immediately followed by an eruption; and explosive eruptions may begin with little warning.
Magma reservoirs typically accumulate over hundreds to thousands of years. Yet, geochemical analyses of volcanic rocks from Campi Flegrei suggest activity there was triggered by injections of volatile-rich magma only days before the eruption.
Journal Article
Caldera resurgence during the 2018 eruption of Sierra Negra volcano, Galápagos Islands
Recent large basaltic eruptions began after only minor surface uplift and seismicity, and resulted in caldera subsidence. In contrast, some eruptions at Galápagos Island volcanoes are preceded by prolonged, large amplitude uplift and elevated seismicity. These systems also display long-term intra-caldera uplift, or resurgence. However, a scarcity of observations has obscured the mechanisms underpinning such behaviour. Here we combine a unique multiparametric dataset to show how the 2018 eruption of Sierra Negra contributed to caldera resurgence. Magma supply to a shallow reservoir drove 6.5 m of pre-eruptive uplift and seismicity over thirteen years, including an Mw5.4 earthquake that triggered the eruption. Although co-eruptive magma withdrawal resulted in 8.5 m of subsidence, net uplift of the inner-caldera on a trapdoor fault resulted in 1.5 m of permanent resurgence. These observations reveal the importance of intra-caldera faulting in affecting resurgence, and the mechanisms of eruption in the absence of well-developed rift systems.
The authors here present geodetic and seismic data for a complete eruptive cycle (2005-2018) for Sierra Negra volcano, Galapagos Island. The data shows the largest pre-eruptive inflation (6.5 m) and rates of seismicity ever observed before a basaltic eruption and provides a rare illustration of caldera resurgence mechanisms.
Journal Article
Cryptic evolved melts beneath monotonous basaltic shield volcanoes in the Galápagos Archipelago
Many volcanoes erupt compositionally homogeneous magmas over timescales ranging from decades to millennia. This monotonous activity is thought to reflect a high degree of chemical homogeneity in their magmatic systems, leading to predictable eruptive behaviour. We combine petrological analyses of erupted crystals with new thermodynamic models to characterise the diversity of melts in magmatic systems beneath monotonous shield volcanoes in the Galápagos Archipelago (Wolf and Fernandina). In contrast with the uniform basaltic magmas erupted at the surface over long timescales, we find that the sub-volcanic systems contain extreme heterogeneity, with melts extending to rhyolitic compositions. Evolved melts are in low abundance and large volumes of basalt flushing through the crust from depth overprint their chemical signatures. This process will only maintain monotonous activity while the volume of melt entering the crust is high, raising the possibility of transitions to more silicic activity given a decrease in the crustal melt flux.
In this study the authors show that monotonous basaltic volcanoes can host a range of melts in their sub-volcanic systems, extending to rhyolitic compositions. The study implies that volcanoes which have produced monotonous basaltic lavas on long timescales could transition to more explosive, silica-rich eruptions in the future.
Journal Article