Sporadic Eruptions Research Articles

Land Bridges and Rafting Theories to Explain Terrestrial-Vertebrate Biodiversity on Madagascar.

Madagascar's celebrated land-vertebrate assemblage has long been studied and discussed. How the ancestors of the 30 different lineages arrived on the island, which has existed since 85 Mya and is separated from neighboring Africa by 430 km of water, is a deeply important question. Did the colonizations take place when the landmass formed part of Gondwana, or did they occur later and involve either now-drowned causeways or overwater dispersal (on vegetation rafts or by floating/swimming)? Following a historical review, we appraise the geological-geophysical evidence and the faunal-suite colonization record. Twenty-six of the clades are explained by temporally stochastic overwater dispersals, spanning 69-0 Mya, while two others are considered Gondwanan vicariant relicts. Due to a lack of information, the remaining two groups cannot be evaluated. The findings thus appear to resolve a debate that has rumbled along, with sporadic eruptions, since the mid-1800s.

Лейшманиоз плотоядных юга России и региона Тосканы (Италия). Некоторые особенности скрининга и профилактики

The purpose of the research is studying leishmaniosis peculiarities of carnivores in Russia and Italy. Materials and methods . 2000 samples of sera were studied with antigen from Leishmania (Roma) at the IFAT, Italy, 174 samples in crystallographic tests, 76 samples from the dogs from Italy, 52 samples from different preying animals and 46 samples from the dogs were studied in ELISA with an antigen from Toxocara sp. and Trichinella sp. (VNIIP). Results and discussion . Leishmaniosis was registered in the RF in Dagestan, Crimea and etc. Currently leishmaniosis of dogs is widely spread in the peninsular and insular Italy. Sporadic eruptions occur to the east from the Apennines, in central Italy and in some regions of the North Piedmont and Aosta Valley, and in the provinces Verona, Brescia and Rimini. Many occasions were registered in Tuscany. A leishmaniosis control is mainly based on identification and treatment of infected dogs in combination with a transmitter control and a control over animal bowls. Over 30% of samples were positive in Italy and 0.7% of samples were positive in the south of Russia. Over 80% of sera that reacted with leishmaniosis antigen (1/160 and more) reacted in enzyme immunoassay EIA with Toxocara sp. and Trichinella sp. antigens. The obtained data on sporadic occasions in the south of Russia evidence the need for epidemiologic, epizootological and entomological investigations in specified areas and for the development of an epidemiologic surveillance system for leishmaniosis covering all the complex of antiepidemic measures.

Moving past sporadic eruptions, discursive killing, and running amok: recognizing the convergence of the serial and spree killer

PurposeRapid sequence homicide offenders (RSHOs), formerly spree killers, are an understudied population due to the confusion surrounding their classification in relation to serial murderers. The paper aims to discuss this issue.Design/methodology/approachAn exploratory, comparative analysis of 56 RSHOs and 60 serial murderers was conducted on US-based data from 2014 to 2018 derived from the Consolidated Serial Homicide Offender Database to determine similarities and differences between the cohorts.FindingsRSHOs and serial murderers are similar in that they often kill their victims using a singular method, have limited mobility, kill a similar number of victims both known and unknown to them and are both supremely motivated by domestic anger. There is an inverse relationship between serial murderers and RSHOs: as one group increases in prevalence the other decreases.Practical implicationsIn order to divert men into more pro-social activities, attention must be dedicated to increasing mental health services that provide them with the tools to diffuse their hatred and couple that with effective gun control strategies and ways to enhance the compromised anger management skills of a generation of volatile men.Originality/valueAcademicians have been hesitant to juxtapose these offenders but based this conclusion on surface-level differences. A reimagining of these categorical structures is needed. The once clear delineation between these cohorts may continue to shrink and synchronize until one subsumes the other.

South Africa’s foreign and migration policies missteps: fuels of xenophobic eruptions?

South Africa plays a crucial role in the development of the African continent, especially in the South African Development Community. Hence, South Africa’s foreign and migration policies shape the perceptions of both its citizens and those of neighbouring states. Since 1994, South Africa has continued to attract the highest number of migrants in the region. The widespread perceptions among South Africans that there are “floods” of illegal immigrants, stealing their jobs and depleting social and economic resources, is a course for concern. Undoubtedly, the South African society is under pressure to effectively respond to the sporadic eruptions of xenophobic attacks on African foreign nationals. This article argues that the missteps of South Africa’s foreign and migration policies partially contribute towards fuelling xenophobic attacks on foreign nationals. The findings of this article suggest that South Africa is not as committed to rooting out xenophobia as it would have us believe.

TEPC reference measurements at aircraft altitudes during a solar storm

The Sun goes through cycles of high and low activity that repeats approximately every 11 years. The solar activity is correlated to the number of dark spots on the Sun which are sources of sudden, sporadic eruptions, releasing energetic particles into space. This can directly affect the ionosphere and radio communications around the Earth. A spectacular and unusually high sunspot activity occurred during October and November 2003, commonly referred to as the Halloween Storms. The increased radiation exposure at aircraft altitudes during such an event is of major concern to international aviation organizations, airlines, governmental authorities and aircraft crew as well as flight passengers. Here, we report radiation exposure measurements made by ARC Seibersdorf research (ARCS) onboard commercial aircraft using a tissue equivalent proportional counter (TEPC). A unique set of long-term measurements was collected before, during and after the storm at flight altitudes. The results of these investigations give an understanding of the combined effects of magnetic field disturbances and solar particle fluence due to a solar storm, showing a 70% variation in the radiation exposure at typical flight altitudes. Whilst several predictive codes exist the radiation exposure to aircrew during a solar storm is difficult to predict by calculation models. These calculation models are still struggling with the high uncertainty of spectral input data provided by satellites during a solar storm. A reliable dose assessment concept to assess the radiation exposure to aircrew caused by a solar storm using a network of dosimeter instruments on-board several aircraft can be achieved. Such a proposal has been already introduced by experts of the European Radiation Dosimetry Group (EURADOS).

Seamounts at the continental margin of California: A different kind of oceanic intraplate volcanism

Davidson, Guide, Pioneer, Gumdrop, and Rodriguez Seamounts, located at the continental margin offshore California between latitudes 37.5°N and 34.0°N, may represent a previously unrecognized type of intraplate oceanic volcanism. Morphologically unlike typical oceanic-island volcanoes or near-ridge seamounts, they are complex, northeast-trending ridges that reflect the ridge-parallel structure of the underlying oceanic crust. 40Ar/39Ar laser fusion ages of mineral separates indicate at least two episodes of volcanism at ca. 16 and ca. 12 Ma, younger by 7–11 m.y. than the underlying ocean crust. Volcanic rocks are predominantly differentiated alkalic basalt, hawaiite, and mugearite. The lack of coherent liquid- lines-of-descent is consistent with small batches of magma forming, fractionally crystallizing, and erupting in isolation from the previous and subsequent batches. The presence of mantle xenoliths suggests that magmas originated in the upper mantle. Xenoliths of alkalic cumulates and xenocrysts of feldspar, amphibole, and titanomagnetite are consistent with fractionation in the upper mantle as well. Sr, Nd, and Pb isotope ratios of some samples are from depleted-mantle sources like those of MORB (mid-oceanic-ridge basalt); others indicate more variably enriched mantle sources. Magmas formed by small- percentage partial melting of variably enriched MORB-source-type mantle, according to the samples' high abundances of incompatible elements such as Nb, Ta, and Th. Coeval middle Miocene basalts in onshore coastal California have a similar isotopic range, but their trace elements show a subduction-related signature. If the coeval volcanic rocks offshore originated in a slab window, as proposed for those onshore, they were not influenced by a slab component. Although a slab-window origin is plausible for the middle Miocene volcanism, later episodes of small, sporadic eruptions on- and offshore probably resulted from decompression melting of mantle rising along existing zones of weakness undergoing extension related to continued movement along transform-fault systems.

Mouse population eruptions in New Zealand forests: the role of population density and seedfall

Summary 1. Sporadically eruptive house mouse populations provide an opportunity to test ideas about how intrinsic and extrinsic factors interact to limit rodent populations. New Zealand house mouse populations inhabiting beech forests and associated mosaics erupt when autumn beech seedfall is high. We analysed 25 years of data on mouse density and beech seedfall from a beech and podocarp/hardwood forest mosaic in New Zealand to test the effects of mouse density, beech seedfall and rat density on rates of change in mouse abundance, estimated as the rate of change in a density index for sequential seasonal transitions (r). 2. For autumn to winter and winter to spring transitions, r was related to the magnitude of autumn seedfall and mouse density at the start of each transition, regardless of whether forest types were considered separately or together. For spring to summer and summer to autumn transitions, r was related to mouse density alone. Density dependence could reflect the influence of intrinsic social factors, intraspecific competition for food, or the effects of parasites, diseases or predators. 3. We modified a conceptual model of variation in rodent reproductive effort to derive a general model of how numerical responses to density‐independent increases in food availability, modified by density‐dependent mechanisms and extrinsic precursors to population increase, drive sporadic eruptions in the density of some rodent populations. For house mice in New Zealand, the numerical response to seedfall was modified by some unidentified density‐dependent mechanism(s) to generate sporadic eruptions. Extrinsic precursors to population increase appear to be important in other eruptive house mouse populations. 4. House mouse density in beech forest was more volatile than in podocarp/hardwood forest, maximum rates of increase and decrease being higher in the former. Density tended to be higher in podocarp/hardwood forest when overall density was low, and higher in beech forest when overall density was high. This suggests that between eruptions, mice persist in podocarp/hardwood forest at higher densities than in adjoining beech forest.

Physical Mechanism of Comet Outbursts: An Experimental Result

During experimental impacts into regoliths in vacuo at NASA Ames Research Center, an explosive eruption of gas-charged powder was observed and photographed. Analysis gives four main results applicable to comets: (1) Loose regoliths can retain interstitial gas pressure, supporting recent comet mantle theories. (2) The observed eruption could have produced a dust coma around a comet nucleus larger than a few kilometers. (3) The eruption involved discrete jets emitted by one primary vent (site of the initial disturbance) rather than a uniform spray from the vent or uniform dust/gas flow from the entire regolith surface. This behavior may clarify the discrete jets from P/Halley and other nuclei, but it is not well described in recent mathematical models of comet "mantles." (4) As discussed earlier by the author and colleagues, the mechanism for sporadic eruptions on comets probably involves gas pressure buildup in the porespace of regoliths having a slight effective tensile strength; outbursts occur spontaneously when pressure exceeds tensile strength. This model explains the recharge mechanism required by intermittent outbursts on P/Schwassmann-Wachmann 1, 2060 Chiron, and other bodies—a mechanism not well described by some mathematical models. This work is generally consistent with a 1990 comet regolith model by H. Rickman, J. Fernandez, and B. Gustafson ( Astron. Astrophys. 237, 524-535) and supports 1992 observations by A.D. Storrs, A. L. Cochran, and E. S. Barker ( Icarus 98, 163-178), who interpret their data as requiring "a porous … mantle of nonnegligible tensile strength." Such experiments may lead to improved theoretical modeling of comet mantle behavior.

Lava flows on Mars: Analysis of small surface features and comparisons with terrestrial analogs

Small‐scale surface features on lava flows provide information on the eruption parameters and the volcanic history of the flows in which they occur. High‐resolution images of four sites on Mars reveal lava flows with a different type or combination of features including pressure ridges, tumuli, festoon ridges, and ring ridges. Pressure ridges, tumuli, and pressure plateaus are spaced irregularly and tend to be oriented parallel to flow. They are formed by inflation of small flow lobes and are indicative of compound flows emplaced by sporadic eruptions with low effusion rates. Festoon ridges are oriented transverse to flow direction, mimic the flow margin, and have a regular spacing. Using a model by Fink and Fletcher (1978) and Fink (1980 a) interior viscosity values of approximately 108 Pa s were calculated for festoon ridges tens to hundreds of meters apart and a few meters high on two basalt flows in Iceland and a flow on Mars. This viscosity is comparable to results from similar studies of more silicic flows and suggests that high viscosities are necessary to form large festoon ridges. By analogy to the Icelandic flows, Martian flows containing festoon ridges are considered to be large, single unit basalt flows emplaced through flood‐style eruptions. High viscosity of the basaltic flows may result from cooling, a high crystal content, or low effusion temperatures. Disruption of the surface of some of these large sheet flows possibly by lava‐water interaction is suggested by the presence of ring ridges and rugged terrain consisting of mesa‐like mounds and channel‐like troughs.

Effects of Lake Fertilization by Volcanic Activity on Abundance of Salmon1

Evidence from various sources—tree growth during the past century, chemical composition of waters of various lakes, plankton volumes, size of young salmon migrating seaward— tends to indicate that the fertilization of lake waters in western Alaska by volcanic ash during sporadic eruptions may be an important factor in determining the abundance of sockeye salmon.

Agrarian Tendencies in the Philippines

THE most pressing internal problems of the Philippines arise from the dislocation of its agrarian system. The incessant agrarian conflicts, which periodically attain the proportion of local insurrections, are indicative of a fundamental crisis. Three important peasant uprisings have taken place during the last io years: the Colorums in 1927, the rebellion at Tayug in I93I, the Sakdalistas in 1935. These sporadic eruptions and, even more, the widespread peasant restlessness are symptoms of a chronically unhealthy agrarian system. The peasant distress of the Islands is more than purely an internal problem. It legitimately falls within the scope of the U. S.-Philippines trade commission, which is now studying the economic relations between the two countries with the purpose of recommending adjustments in trade relative to independence. Since 8o per cent of Philippine exports go to a protected American market, the flow of trade has the most direct bearing on the agrarian problem of the Islands. Furthermore, the agrarian problem is necessarily the first concern of the Commonwealth Government and the methods it chooses to meet this problem will largely determine the political complexion of Government policy and the extent of popular support accorded it. These factors are certainly important in determining the position of the Philippines in relation to the dominant forces at conflict in the Pacific area. If the situation be judged purely on the basis of the Philippines' ascending curve of exports during the last two decades, agriculture would not seem to be so badly off. Even at the depth of the economic crisis this curve did not dip nearly as drastically as the exports of most countries, and the recovery was more rapid. But if Philippine agriculture was able to retain its market this was due, above all, to the fact that its crops, particularly sugar, were duty-free in the United States. The maintenance of the high level of agricultural production, made possible by the favored market, undoubtedly cush-

II.—The Red Zone in the Basaltic Series of the County of Antrim

One of the most beautiful features at the Giants' Causeway, from an artistic as well as a geological point of view, is the broad red zone that divides the Lower from the Upper Basalts. As is well known, this zone of lithomarge, bole, and laterite is remarkably persistent in north-eastern Ireland, and represents an interval of Eocene time when volcanic activity was lessened and when the basalts ceased to appear at the surface. At the same time, however, sporadic eruptions of rhyolite occurred, and some of the cones of acid lava supplied material for an interbasaltic conglomerate of rhyolite pebbles, which was discovered several years ago by Mr. A. McHenry near Glenarm.