Formation Of Intrusions Research Articles

Cyclic Slip Irreversibilities and the Evolution of Fatigue Damage

In this article, the physical origin of fatigue crack initiation in ductile metals is discussed from a historical perspective. The main focus is to assess those cyclic slip irreversibilities in a microstructural sense that occur not only at the surface but also in the bulk at the dislocation scale and to show how they contribute to surface fatigue damage. The evolution of early fatigue damage, as evidenced experimentally in the last decades, is reviewed. The phenomenon of cyclic strain localization in persistent slip bands (PSBs) and models of the formation of extrusions, intrusions, and microcracks are discussed in detail. The predictions of these models are compared with experimental evidence obtained on mono- and polycrystalline face-centered-cubic (fcc) metals. In addition, examples of the evolution of fatigue damage in selected fcc solid solution alloys and precipitation-hardened alloys and in body-centered-cubic (bcc) metals are analyzed. Where possible, the cyclic slip irreversibilities p, defined as the fraction of plastic shear strain that is microstructurally irreversible, have been estimated quantitatively. Broadly speaking, p has been found to vary over orders of magnitude (0 < p < 1), being almost negligible at low loading amplitudes (high fatigue lives) and substantial at larger loading amplitudes (low fatigue lives).

Cyclic Slip Irreversibilities and the Evolution of Fatigue Damage

In this article, the physical origin of fatigue crack initiation in ductile metals is discussed from a historical perspective. The main focus is to assess those cyclic slip irreversibilities in a microstructural sense that occur not only at the surface but also in the bulk at the dislocation scale and to show how they contribute to surface fatigue damage. The evolution of early fatigue damage, as evidenced experimentally in the last decades, is reviewed. The phenomenon of cyclic strain localization in persistent slip bands (PSBs) and models of the formation of extrusions, intrusions, and microcracks are discussed in detail. The predictions of these models are compared with experimental evidence obtained on mono- and polycrystalline face-centered-cubic (fcc) metals. In addition, examples of the evolution of fatigue damage in selected fcc solid solution alloys and precipitation-hardened alloys and in body-centered-cubic (bcc) metals are analyzed. Where possible, the cyclic slip irreversibilities p, defined as the fraction of plastic shear strain that is microstructurally irreversible, have been estimated quantitatively. Broadly speaking, p has been found to vary over orders of magnitude (0 < p < 1), being almost negligible at low loading amplitudes (high fatigue lives) and substantial at larger loading amplitudes (low fatigue lives).

Thermochronological models for the evolution of A-type leucogranites in the Neoproterozoic collisional orogen of the Yenisei Ridge

Results of complex geological, petrological, geochemical, and isotope-geochronological studies of Neoproterozoic postcollisional A-type granites of the Glushikha complex, Yenisei Ridge, are presented, as well as results of mathematical modeling. The localization, sizes, and depths of formation of magmatic bodies and the physicochemical conditions of the formation of granite intrusions and their magmatic sources are considered. The research is focused on the modeling of the thermal history of the formation and subsequent cooling of granites in the collision orogen. The modeling of heat transfer during the acid-magma intrusion was performed by the example of the Lendakha and Glushikha leucogranite plutons. With the combined methods of the modeling of heat transfer and the behavior of K/Ar isotopic system, the models for leucogranite pluton cooling have been verified for the first time. The time of formation and cooling of granite bodies is estimated, and a generalized geodynamic model for the formation of the Glushikha postcollisional A-type leucogranites is proposed.

Stalkers and harassers of royalty: the role of mental illness and motivation

Public figures are at increased risk of attracting unwanted attention in the form of intrusions, stalking and, occasionally, attack. Whereas the potential threat to the British Royal Family from terrorists and organized groups is clearly defined, there is a dearth of knowledge about that from individual harassers and stalkers. This paper reports findings from the first systematic study of this group. A retrospective study was conducted of a randomly selected stratified sample (n=275) of 8001 files compiled by the Metropolitan Police Service's Royalty Protection Unit over 15 years on inappropriate communications or approaches to members of the British Royal Family. Cases were split into behavioural types. Evidence of major mental illness was recorded from the files. Cases were classified according to a motivational typology. An analysis was undertaken of associations between motivation, type of behaviour and mental illness. Of the study sample, 83.6% were suffering from serious mental illness. Different forms of behaviour were associated with different patterns of symptomatology. Cases could be separated into eight motivational groups, which also showed significant differences in mental state. Marked differences in the intrusiveness of behaviour were found between motivational groups. The high prevalence of mental illness indicates the relevance of psychiatric intervention. This would serve the health interests of psychotic individuals and alleviate protection concerns without the necessity of attempting large numbers of individual risk predictions. The finding that some motivations are more likely to drive intrusive behaviours than others may help focus both health and protection interventions.

The Variscan evolution in the External massifs of the Alps and place in their Variscan framework

In the general discussion on the Variscan evolution of central Europe the pre-Mesozoic basement of the Alps is, in many cases, only included with hesitation. Relatively well-preserved from Alpine metamorphism, the Alpine External massifs can serve as an excellent example of evolution of the Variscan basement, including the earliest Gondwana-derived microcontinents with Cadomian relics. Testifying to the evolution at the Gondwana margin, at least since the Cambrian, such pieces took part in the birth of the Rheic Ocean. After the separation of Avalonia, the remaining Gondwana border was continuously transformed through crustal extension with contemporaneous separation of continental blocks composing future Pangea, but the opening of Palaeotethys had only a reduced significance since the Devonian. The Variscan evolution in the External domain is characterised by an early HP-evolution with subsequent granulitic decompression melts. During Visean crustal shortening, the areas of future formation of migmatites and intrusion of monzodioritic magmas in a general strike–slip regime, were probably in a lower plate situation, whereas the so called monometamorphic areas may have been in an upper plate position of the nappe pile. During the Latest Carboniferous, the emplacement of the youngest granites was associated with the strike–slip faulting and crustal extension at lower crustal levels, whereas, at the surface, detrital sediments accumulated in intramontaneous transtensional basins on a strongly eroded surface.

Precambrian mafic magmatism in south Indian granulite terrain

South Indian granulite terrain had witnessed significant part of Precambrian mafic igneous activity in the form of episodic mafic dyke intrusions of the Palaeoproterozoic period. Strike trends of these dykes are not uniform over the region and the dykes are generally fresh, massive, black dolerites except in the Bhavani shear zone bordering the southern fringes of Nilgiri massif. In Agali-Coimbatore area of our study in the western Bhavani shear zone, the dykes appear to be penecontemporaneous with shearing. Isotopic data place age of Agali-Coimbatore dyke intrusions at about 2.1 Ga. The age of these dykes is significant to constrain an early Palaeoproterozoic age for major shearing event in the Bhavani shear zone. Other dyke emplacement ages are placed at about 1.8 Ga and 1.65 Ga based on the Ar/Ar and K-Ar isotopic results of dykes in Dharmapuri and Tiruvannamalai areas. Older ages comparable to those of the Dharwar craton are not known and in this respect future isotopic dating is vital. Geochemically, these dykes are quartz/hypersthene normative subalkalic tholeiites. An attempt is made here to provide insights into the general petrogenetic history of the Precambrian dykes. Compositional trends are explained by the fractional crystallization of ferromagnesian phases and plagioclase control is conspicuous at the advanced stages of fractionation. Geochemical characteristics suggest that the dykes have tapped Fe-rich non-pyrolite mantle sources with LIL and LREE enrichment as in many continental basalts. The data suggest that role of crustal contamination is limited in petrogenesis; crustal signatures are noticed in the more mafic end members formed in early stage of evolution suggesting that contamination was temperature controlled with most primitive high temperature magmas being most vulnerable to the process. Nd-Sr isotopic data, at present restricted to Agali-Coimbatore dykes, suggest that Palaeoproterozoic magmas tapped subcontinental lithosphere that may have stabilized in the Archaean times at about 3 Ga during the major crustal building activity in the shield region. Further work coupled with isotopic and mineral chemistry will improve our knowledge on the petrological evolution of the dyke magmas and mafic magmatism in general.

Growth of extrusions in localized cyclic plastic straining

Cyclic strain localization into persistent slip bands produces on the surface of cyclically deformed materials persistent slip markings in the form of extrusions and intrusions. The localized cyclic plastic straining in persistent slip bands leads to the production and annihilation of dislocations as well as point defects. Production, annihilation and migration of point defects, preferably vacancies, is quantitatively characterized. The effect of vacancy production and migration on the extrusion growth is treated under simplified conditions. At low temperatures when vacancies are immobile, a static extrusion is produced. At elevated temperature the diffusion equation is solved, a general expression for stabilized rate of extrusion growth is obtained and temperature dependence of the growth rate can be predicted. The predictions of the model are compared with experimental observations.

Peering into dirty waters: the potential and implications of a new approach to monitoring drug consumption

Peering into dirty waters: the potential and implications of a new approach to monitoring drug consumption

Dykes, cups, saucers and sills: Analogue experiments on magma intrusion into brittle rocks

Magma is transported in the crust by blade-like intrusions such as dykes, sills, saucers, and also collects in thicker laccoliths, lopoliths and plutons. Recently, the importance and great number of shallow (< 5 km) saucer-shaped intrusions has been recognized. Lopoliths and cup-shaped intrusions have also been reported in many geological contexts. Our field observations indicate that many intrusions, especially those emplaced into breccias or fractured rocks, have bulging, lobate margins and have shear faults at their bulbous terminations. Such features suggest that magma can propagate along a self-induced shear fault rather than a hydraulic tension-fracture. To investigate this we use analogue models to explore intrusion propagation in a brittle country rock. The models consist of the injection of analogue magma (honey or Golden syrup) in a granular material (sand or sieved ignimbrite) that is a good analogue for brittle or brecciated rocks. These models have the advantage (over other models that use gelatin) to well represent the properties of brittle materials by allowing both shear-faults and tension fractures to be produced at suitable stresses. In our experiments we mainly obtain vertical dykes and inverted-cone like structures that we call cup-shaped intrusions. Dykes bifurcate into cup-shaped intrusions at depths depending on their viscosity. All cup-shaped intrusions uplift a central block. By injecting against a vertical glass plate we obtain detailed observations of the intrusion propagation style. We observe that dykes commonly split and produce cup-shaped intrusions near the surface and that shear zone-related intrusions develop at the dyke tip. We conclude that many dykes propagate as a viscous indenter resulting from shear failure of host rock rather than tensional hydraulic fracturing of host rocks. The shear propagation model provides an explanation for the shape and formation of cup-shaped intrusions, saucer-sills and lopoliths.

Ecriture romanesque burkinabè: une écriture hétérogène, des textesentre écrit et oral

A French person perusing some Burkinabè novels would undoubtedly be surprised or even baffled by tense transitions. These are often not typical, and the purists of the French language would unquestionably condemn them. Yet, these transitions express the potentials inherent in the French tense system. Some linguistic theories, like Benveniste’s, if not used mechanically and sketchily, may help account for these “turbulence zones,” as some people have labelled them. My paper aims to show how, in most Burkinabè novels, this tense transition game allows for switching from one tense to another: from the Past Perfect (PP) to the Simple Past (SP) and Pluperfect (PLP), from the Present PRES to the Imperfect (IMP), and from the Future (FUT) to the Conditional (COND). This takes place in all narrative spaces, in a perfect linguistic legality. Some have explained these often unpredictable transitions as being the result of a switch between, a telescoping, of two different types of narration, two enunciation points of view of the narrator (linked diegesis and autonomous diegesis). However, this switching-telescoping may also be interpreted as the narrator oscillating between a written narration and an oral narration. We see this phenomenon as a form of intrusion or irruption, not necessarily a conscious one, of orality into writing. Hence, Burkinabè novels are heterogeneous in nature, evolving between writing and orality, and this is one of the manifest trends of novel writing in Burkina Faso.&nbsp

The Burkinabè novel: heterogeneous writing, texts located between written and oral forms

A French person perusing some Burkinabe novels would undoubtedly be surprised or even baffled by tense transitions. These are often not typical, and the purists of the French language would unquestionably condemn them. Yet, these transitions express the potentials inherent in the French tense system. Some linguistic theories, like Benveniste's, if not used mechanically and sketchily, may help account for these “turbulence zones,” as some people have labelled them. My paper aims to show how, in most Burkinabe novels, this tense transition game allows for switching from one tense to another: from the Past Perfect (PP) to the Simple Past (SP) and Pluperfect (PLP), from the Present PRES to the Imperfect (IMP), and from the Future (FUT) to the Conditional (COND). This takes place in all narrative spaces, in a perfect linguistic legality. Some have explained these often unpredictable transitions as being the result of a switch between, a telescoping, of two different types of narration, two enunciation points of view of the narrator (linked diegesis and autonomous diegesis). However, this switching-telescoping may also be interpreted as the narrator oscillating between a written narration and an oral narration. We see this phenomenon as a form of intrusion or irruption, not necessarily a conscious one, of orality into writing. Hence, Burkinabe novels are heterogeneous in nature, evolving between writing and orality, and this is one of the manifest trends of novel writing in Burkina Faso. Keywords : Verbal temporality, semantics, discourse analysis, francophone literature. > Tydskrif vir Letterkunde Vol. 44 (1) 2007 pp. 51-69

The Mystery of Delaware Law's Continuing Success

This Article challenges the widely held view that Delaware corporate law is dominant because it possesses superior traits, such as a well-understood statute, many judicial decisions interpreting the law, and wise and experienced judges administering that law. The authors evaluate superiority by the measure first identified by Romano as the relevant one for jurisdictional choice-reducing transactions costs in major transactions. The authors show that since the 1980s Delaware law has become increasingly complex and uncertain, due largely to judicial decisions that appear to tailor doctrines to produce fairness in individual cases, at the expense of certainty in planning and executing transactions. The result has been a variety of mini-rules that require firms and their lawyers to structure transactions formalistically to avoid the most intrusive forms of judicial review. These rules have led to a litigation explosion in Delaware, with concomitant high litigation costs. The authors also demonstrate the weaknesses of the Delaware General Corporation Law as compared to the Model Business Corporation Act. Finally, the authors examine and reject a series of apologies for Delaware law by commentators who concede at least some of these problems.

Debt, Development and Intervention in Africa: The Contours of a Sovereign Frontier

This paper argues that the concept of the sovereign frontier can help us think about sovereignty and intervention in a way that moves beyond some of the limitations usually associated with the former concept. Focused on a zone of practice, embedded in a broader ‘movement’ of Western expansion, the sovereign frontier highlights political practices of subordination and incorporation that characterize the sway of intervention in contemporary African states. These concepts are sketched out with reference to more concrete practices of intervention in African states – especially ‘governance states’ – and critical commentary is drawn therefrom. The main argument here is that a series of ostensibly less intrusive forms of aid policy-making are enabled by a constitutive inequality within the sovereign frontier and work towards a more profound and effective projection of external power within it. The paper concludes by suggesting that the intrinsic expansiveness of the sovereign frontier offers few possibilities for the attainment of alternative sovereignties to those shaped by Western institutions.

Mechanisms and kinetics of the early fatigue damage in crystalline materials

The localization of the cyclic plastic strain and its effect on the hysteresis loop, on the surface relief evolution and on the internal dislocation structure of austenitic and ferritic stainless steels are presented. Extrusion and intrusion formation is studied using atomic-force microscopy. The experimental findings concerning the surface relief formation and crack evolution are confronted with existing models of fatigue-crack initiation. Short crack growth kinetics is documented and the short crack growth law and its parameters are compared with the Coffin–Manson law.

Give Me Equity or Give Me Death - The Role of Competition and Compensation in Building Silicon Valley

In this essay, I argue that the preeminence of Silicon Valley as an incubator of technology companies is attributable to equity compensation. Ronald Gilson, relying on the work of AnnaLee Saxenian and others who have noted the tendency of Silicon Valley employees to job hop, has suggested that California law prohibiting the enforcement of non-compete agreements was a major factor in the rise of Silicon Valley (and the demise of Route 128). I extend this line of thought by suggesting that California employers may have relied on equity compensation as a substitute way to bind employees. I argue further that equity compensation (in its many forms) is a superior way to assure the loyalty of employees. First, equity compensation induces employees to focus on how their efforts will contribute to the success of the business. Second, equity compensation saves cash for the startup firm and permits firms to compete for talent without offering more cash. Third, equity compensation forces the company to seek and plan for liquidity. Fourth, equity compensation induces employees to consider the prospects of the employer firm and thus induces employer firms to consider the ideas of employees. In addition, equity compensation may induce employees to exit unpromising ventures sooner rather than later thus allocating resources more efficiently. Fifth, equity compensation induces firms to maintain an efficient size. If a firm grows too large, too diversified, or too unfocused, equity compensation will become less attractive for employees. Thus, equity compensation will tend to induce spin-offs and other divisive transactions. Finally, equity compensation may be an efficient substitute for more intrusive forms of dispute resolution such as fiduciary duty. Employees will be less tempted to cut and run if they must give up bird-in-hand equity. Moreover, equity compensation is more fine-tuned than non-compete agreements. Whereas most non-compete agreements have a specified duration, equity compensation will effectively bind an employee only as long as necessary to assure the success of the venture.

Pliocene granitoid massif in the Kazbek volcanic center: First geochronological and isotope-geochemical data

Detailed study of Late Cenozoic intrusive magmatism in the Earth remains one of the most pressing and interesting geological problems of both regional and fundamental significance. For example, data on recent plutonic rocks with a short-term modern history can be used to solve important problems, such as the duration of crystallization and cooling of different (in volume and composition) intrusive bodies, recognition of discrete intrusive phases for plutons formed in geologically short intervals, determination of subtle isotope‐ geochemical differences between rocks of different intrusive phases, and so on. The present paper is devoted to the geochronological and isotope‐geochemical study of one of the reference (but insufficiently studied) terranes of young granitoid magmatism in the Kazbek neovolcanic area of the Greater Caucasus. Data obtained suggests the existence of a single intrusive massif in the area. They make it possible to determine its timing, major petrochemical characteristics of granitoids, and possible sources of magmatic melts. At the Greater Caucasus and its northern periphery, one can distinguish three stages of Late Cenozoic activity (Late Miocene, Pliocene, and Anthropogene) [1‐7 and others]. Pliocene magmatism was mainly expressed in the formation of hypabyssal granite or granodiorite intrusions, as well as usually differentiated (from diorite to granites) intrusive massifs. The Elbrus neovolcanic area incorporates two granitoid massifs (Eldzhurtu and Dzhungusu), for which a great number of isotope, geochronological, isotope‐geochemical, and thermochronological data are available [3, 4, and others]. Pliocene intrusive massifs in the Kazbek volcanic area, including the most well-known Tepli and Songuti-Don massifs, have been studied less. In the Kazbek area, plutonic bodies are typically localized in the sublatitudinal zone between Skalistyi Ridge in the north and the Main Caucasus Range in the south. The zone is extended from Mt. Shkhara in the west to Kazbek Volcano in the east. In addition, several small massifs are known on the southern slope of the Main Caucasus Range (Tsurungal, Karobi, and Kalkva). This vast area also includes numerous dikes varying in composition from granite porphyries to subalkaline diabases. Probably, some of them mark the paleovolcanic edifices

Surface Kuroshio path in the Luzon Strait area derived from satellite remote sensing data

Satellite ocean color, sea surface temperature, and altimeter data are used to study the surface Kuroshio path in the Luzon Strait area. The results suggest that the dominant path of surface Kuroshio intrusion in winter is a direct route from northeast of Luzon to southwest of Taiwan and then westward along the continental slope of northern South China Sea. Anticyclonic intrusions of the Kuroshio in the Luzon Strait area are observed during less than 30% of the time on average and in all four seasons of the year. Winter is the most favorable season for the formation of the anticyclonic intrusions. However, the Kuroshio is observed to deviate from the dominant path during only a little over one third of the wintertime on average. The loop currents of the Kuroshio, which feature prominent inflow‐outflow currents in the Luzon Strait during the anticyclonic intrusions, are observed only occasionally, with more episodes in summer than in winter. The observation of more frequent loop currents of the Kuroshio in summer than in winter is a revision to the existing conclusion. These results demonstrate that the anticyclonic intrusion of the Kuroshio is a transient phenomenon rather than a persistent circulation pattern in the Luzon Strait area as suggested by some of the existing numerical model simulations. The growth and decay of the anticyclonic intrusions of the Kuroshio are closely related to the passages and evolution of mesoscale eddies in the Luzon Strait area. Each anticyclonic intrusion event lasts for a few weeks. Its termination sometimes results in a detached anticyclonic eddy propagating to the western basin along the continental slope of the northern South China Sea.

Worm damage minimization in enterprise networks

Attackers utilize many forms of intrusion via computer networks; currently, worms are an important vector with the potential for widespread damage. None of the strategies is effective and rapid enough to mitigate worm propagation. Therefore, it is extremely important for organizations to better understand worm behaviour and adopt a strategy to minimize the damage due to worm attacks. This paper describes an approach to minimize the damage due to worm infection in enterprise networks. The approach includes: (1) analyzing the effect of parameters influencing worm infection: openness, homogeneity, and trust, (2) predicting the number of infected nodes by fuzzy decision, and (3) optimizing the trust parameter to minimize the damage by fuzzy control. Experiments using real worm attacks show that the selected parameters are strongly correlated with actual infection rates, the damage prediction produces accurate estimates, and the optimization of the selected parameter can lessen the damage from worm infection.

Nicholas Murray Butler, the Carnegie Endowment for International Peace, and the Search for Reconciliation in Europe, 1919–1933

The mission of the Carnegie Endowment for International Peace (CEIP) changed in fundamental ways in the 1920s. In the wake of the Great War, Nicholas Murray Butler, the CEIP's second president, decided that the institution's prewar focus on research and legalism was insufficient to meet the threat posed to “civilization” by continued war and revolution. Under his leadership, the CEIP became an active proponent of Wilsonianism, a more intrusive form of American internationalism. This article examines Butler's understanding of the purpose of conservative peace institutions in revolutionary times. It also aims to contribute to our understanding of the role of nongovernmental organizations in international relations and the development of cultural relations.

Interannual variability of the Kuroshio intrusion in the South China Sea

The interannual variability of intrusions of the Kuroshio into the South China Sea (SCS) is investigated using satellite remote sensing data supported by in-situ measurements. The mesoscale circulation of the SCS is predominantly wind-forced by the northeast winter and southwest summer monsoons. Although the region has been studied extensively, considerable uncertainty remains about the annual and interannual mesoscale nature of the circulation. The frequency and characteristics of Kuroshio intrusions and their effect on circulation patterns in the northeast SCS are also not well understood. Satellite observations of Sea Surface Temperature (SST) from the Tropical Rainfall Measuring Mission (TRMM) and the Advanced Very High Resolution Radiometer (AVHRR) and Sea Surface Height Anomalies (SSHA) from TOPEX/ Poseidon for the period 1997–2005 are used here to analyze the annual and interannual variability in Kuroshio intrusions and their effects on the region. Analysis of SST and SSHA shows the formation and characteristics of intrusions vary considerably each year. Typically, the intrusion occurs in the central region of Luzon Strait and results in an anticyclonic circulation in the northeastern SCS. However, in some years, the intrusion is located in the northern portion of Luzon Strait and a cyclonic intrusion results. Wind stress and wind stress curl derived from the National Aeronautics and Space Administration (NASA) QuikSCAT satellite scatterometer are used to evaluate the relationship between wind stress or wind stress curl and the presence of winter Kuroshio intrusions into the SCS.