Explosive Expansion Research Articles

Axisymmetric solutions of the Chaplygin gas for initial negative radial velocity

In this paper, a three-parameter family of self-similar and weak solutions are constructed rigorously in two space dimensions for all positive time to the Euler equations with axisymmetric and radial negative initial velocity for the Chaplygin gas. Under the axisymmetry and self-similar assumptions, the equations are reduced to a system of three ordinary differential equations, from which we obtain structures of solutions besides their existence. The solutions exhibit some phenomena, such as formation and evolution of black hole, expansion and explosive expansion, in the evolution of universe.

Erratum to: Explosive Expansion of βγ-Crystallin Genes in the Ancestral Vertebrate

The online version of the original article can be found under doi:10.1007/s00239-010-9379-2.

Explosive Expansion of βγ-Crystallin Genes in the Ancestral Vertebrate

In jawed vertebrates, βγ-crystallins are restricted to the eye lens and thus excellent markers of lens evolution. These βγ-crystallins are four Greek key motifs/two domain proteins, whereas the urochordate βγ-crystallin has a single domain. To trace the origin of the vertebrate βγ-crystallin genes, we searched for homologues in the genomes of a jawless vertebrate (lamprey) and of a cephalochordate (lancelet). The lamprey genome contains orthologs of the gnathostome βB1-, βA2- and γN-crystallin genes and a single domain γN-crystallin-like gene. It contains at least two γ-crystallin genes, but lacks the gnathostome γS-crystallin gene. The genome also encodes a non-lenticular protein containing βγ-crystallin motifs, AIM1, also found in gnathostomes but not detectable in the uro- or cephalochordate genome. The four cephalochordate βγ-crystallin genes found encode two-domain proteins. Unlike the vertebrate βγ-crystallins but like the urochordate βγ-crystallin, three of the predicted proteins contain calcium-binding sites. In the cephalochordate βγ-crystallin genes, the introns are located within motif-encoding region, while in the urochordate and in the vertebrate βγ-crystallin genes the introns are between motif- and/or domain encoding regions. Coincident with the evolution of the vertebrate lens an ancestral urochordate type βγ-crystallin gene rapidly expanded and diverged in the ancestral vertebrate before the cyclostomes/gnathostomes split. The β- and γN-crystallin genes were maintained in subsequent evolution, and, given the selection pressure imposed by accurate vision, must be essential for lens function. The γ-crystallin genes show lineage specific expansion and contraction, presumably in adaptation to the demands on vision resulting from (changes in) lifestyle.Electronic supplementary materialThe online version of this article (doi:10.1007/s00239-010-9379-2) contains supplementary material, which is available to authorized users.

On the Annotation of Web Videos by Efficient Near-Duplicate Search

With the proliferation of Web 2.0 applications, user-supplied social tags are commonly available in social media as a means to bridge the semantic gap. On the other hand, the explosive expansion of social web makes an overwhelming number of web videos available, among which there exists a large number of near-duplicate videos. In this paper, we investigate techniques which allow effective annotation of web videos from a data-driven perspective. A novel classifier-free video annotation framework is proposed by first retrieving visual duplicates and then suggesting representative tags. The significance of this paper lies in the addressing of two timely issues for annotating query videos. First, we provide a novel solution for fast near-duplicate video retrieval. Second, based on the outcome of near-duplicate search, we explore the potential that the data-driven annotation could be successful when huge volume of tagged web videos is freely accessible online. Experiments on cross sources (annotating Google videos and Yahoo! videos using YouTube videos) and cross time periods (annotating YouTube videos using historical data) show the effectiveness and efficiency of the proposed classifier-free approach for web video tag annotation.

Pyroxene-selective impact smelting in ureilites

A characteristic feature of ureilite meteorites is reduction of FeO. But the reduction is usually confined to the rims of olivine. In the LAR 04315, LAP 03587 and Almahata Sitta ureilites, pyroxene was extensively reduced by impact smelting. In LAR 04315, the impact caused nearly all of the original pigeonite to melt or otherwise become sufficiently structurally compromised to allow smelting, and yet a minor proportion of the pyroxene escaped smelting and survived with its original composition (En 74.1Wo 10.2). Olivine mosaicism confirms that LAR 04315 experienced a major shock event. The smelted pyroxenes also show a distinctive patchiness in their interference colors (although each grain’s basic optical continuity, often including twinning, is still discernible). They also have reduced compositions, are ubiquitously porous (∼15%), and contain sprinklings of Fe-metal and felsic glass. For the most part the olivine underwent only very slight reduction. Much of the (small) pyroxene component of LAP 03587 shows the same oddly porous texture. LAR 04315 also contains large traces of silica and felsic glass (with a typical composition of, in wt%, 61 SiO 2, 23 Al 2O 3, 11 CaO, 3.7 Na 2O) glass; these two phases together form selvages that line the walls of many of the largest voids in the rock. Silica is a by-product of pyroxene smelting. The felsic glass probably derives largely from interstitial basaltic melt that predated the impact. However, the comparatively stiff surrounding/included silica may have promoted unusually high melt retention within LAR 04315 through the smelting episode (one aspect of which was a major stream-out, through the same large voids, of CO x gas). The impact-smelted pyroxene of LAP 03587 is enigmatic because this ureilite also features little-shocked euhedral graphite laths and no olivine mosaicism. The fine-grained ureilitic component of Almahata Sitta appears to have likewise formed by impact smelting, but with more extensive melting of pyroxene (especially a Ca-rich pyroxene component), more pulverization and melting of olivine, and more displacement of both. However, in places the original coarse-equant ureilite texture is still discernible in relict form. Ordinarily, an impact shock melts olivine before, or at least no later than, pyroxene. But in the case of LAR 04315 and LAP 03587, the great shock event evidently occurred when the material was already anatectic or very nearly so; and thus the difference in melting temperature between pyroxene and olivine, ∼300 degrees lower for pyroxene, was decisive. If literature inferences of extremely fast cooling rates, implying shallow burial depths, are accurate, the proportion of CO x gas generated by ureilite smelting exceeded by a very large factor (of order 10 3 but possibly much greater) the volume represented as porosity in the final ureilites. The outflow of so much gas may have, by near-surface explosive expansion and jetting, enhanced the thoroughness of the impact-triggered catastrophic impact disruption of the parent asteroid.

Spatial-temporal dynamics of auroras during the magnetic storm main phase

The structure and dynamics of auroras in the midnight sector during substorms, which develop during the magnetic storm main phase as compared to the characteristics of a typical auroral substorm, have been studied using the ground-based and satellite observations. It has been found out that a difference from the classical substorm is observed in auroras during the magnetic storm main phase. At the beginning of the storm main phase, the series of pseudobreakups with the most pronounced jump-like motion toward the equator shifts to lower latitudes. The substorm expansion phase can be observed not only as arc jumps to higher latitudes but also as an explosive expansion of a bright diffuse luminosity in all directions. During the magnetic storm main phase, auroras are mainly characterized by the presence of stable extensive rayed structures and by the simultaneous existence of different auroral forms, typical of different substorm phases, in the TV camera field of view.

Multibubble cavitation inception

The inception of cavitation in multibubble cases is studied numerically and theoretically to show that it is different from that in single-bubble cases in several aspects. Using a multibubble model based on the Rayleigh–Plesset equation with an acoustic interaction term, we confirmed that the recently reported suppression of cavitation inception due to the interaction of nonidentical bubbles can take place not only in liquid mercury but also in water, and we found that a relatively large bubble can significantly decrease the cavitation threshold pressure of a nearby small bubble. By examining in detail the transition region where the dynamics of the suppressed bubble changes drastically as the interbubble distance changes, we determined that the explosive expansion of a bubble under negative pressure can be interrupted and turn into collapse even though the far-field liquid pressure well exceeds the bubble’s threshold pressure. Numerical results suggest that the interruption of expansion occurs when the bubble radius is exceeded by the instantaneous unstable equilibrium radius of the bubble determined using the total pressure acting on the bubble. When we extended the discussion to systems of larger numbers of bubbles, we found that a larger number of bubbles have a stronger suppression effect. The present findings would be useful in understanding the complex behavior of cavitation bubbles in practical applications where, in general, many cavitation nuclei exist and may interact with each other.

Applying Semiotics and Information Theory to Biology: A Critical Comparison

Since the beginning of the XX-th century, it became increasingly evident that information, besides matter and energy, is a major actor in the life processes. Moreover, communication of information has been recognized as differentiating living things from inanimate ones, hence as specific to the life processes. Therefore the sciences of matter and energy, chemistry and physics, do not suffice to deal with life processes. Biology should also rely on sciences of information. A majority of biologists, however, did not change their mind and continued to describe life in terms of chemistry and physics. They merely borrowed some vocabulary from the information sciences. The first science of information available to biological applications, semiotics, appeared at the end of the XIX-th century. It is a qualitative and descriptive science which stemmed from efforts of linguists and philosophers to understand the human language and is thus mainly concerned with semantics. Applying semiotics to biology resulted in today’s Biosemiotics. Independently, an explosive expansion of communication engineering began in the second half of the XX-th century. Besides tremendous progresses in hardware technology, it was made possible by the onset of a science of literal communication: Information Theory (Shannon, Bell Syst Tech J 27:379–457, 623–656, 1948). Literal communication consists of faithfully transporting a message from a place to another, or from an instant to another. Because the meaning of a message does not matter for its transportation, information theory ignores semantics. This restriction enables defining information as a measurable quantity on which a mathematical theory of communication is founded. Although lacking implementation means at its beginning, information theory became later very successful for designing communication means. Modern ones, like mobile phones, can be thought of as experimentally proving the relevance and accuracy of information theory since their design and operation heavily rely on it. Information theory is plainly relevant to biological functions which involve literal communication, especially heredity. This paper is intended to compare the two approaches. It shows that, besides obvious differences, they have some points in common: for instance, the quantitative measurement of information obeys Peirce’s triadic paradigm. They also can mutually enlighten each other. Using information theory, which is closer to the basic communication mechanisms, may appear as a preliminary step prior to more elaborated investigations. Criticizing genetics from outside, information theory furthermore reveals that the ability of the template-replication paradigm to faithfully conserve genomes is but a prejudice. Heredity actually demands error-correcting means which impose severe constraints to the living world and must be recognized as biological facts.

Research of Cathode Plasma Speed in Planar Diode With Explosive Emission Cathode

The research results of the speed dynamics of explosive emission plasma expansion in the planar diode with cathodes made of graphite, carbon fiber, and copper (solid and multiedged) and with the multiedged tungsten cathode are presented. The plasma speed was determined by the volt-ampere characteristics of the diode with a time resolution of 0.2 ns. The experiments have been performed at the electron accelerator TEU-500 (350-450 kV, 100 ns, and 10 kA). It was found out when the plasma formation at the cathode is completed, and until the pulse ends, the plasma speed is constant and equal to 2 plusmn 0.5 cm / mus for graphite and carbon fiber cathode, 3 plusmn 0.5 cm /mus for tungsten cathode, and 4 plusmn 0.5 cm / mus for cathode made of copper. The analysis of various mechanisms of anode plasma action on the deviation of electron current from the value described by the correlation of Child-Langmuir-reduction of anode-cathode gap, compensation of volumetric electron charge, and additional input of electrons and ions of anode plasma to the total diode current-has been performed.

Mitochondrial and microsatellite DNA markers reveal a Balkan origin for the highly invasive horse‐chestnut leaf miner Cameraria ohridella (Lepidoptera, Gracillariidae)

Biological invasions usually start with a small number of founder individuals. These founders are likely to represent a small fraction of the total genetic diversity found in the source population. Our study set out to trace genetically the geographical origin of the horse-chestnut leafminer, Cameraria ohridella, an invasive microlepidopteran whose area of origin is still unkown. Since its discovery in Macedonia 25 years ago, this insect has experienced an explosive westward range expansion, progressively colonizing all of Central and Western Europe. We used cytochrome oxidase I sequences (DNA barcode fragment) and a set of six polymorphic microsatellites to assess the genetic variability of C. ohridella populations, and to test the hypothesis that C. ohridella derives from the southern Balkans (Albania, Macedonia and Greece). Analysis of mtDNA of 486 individuals from 88 localities allowed us to identify 25 geographically structured haplotypes. In addition, 480 individuals from 16 populations from Europe and the southern Balkans were genotyped for 6 polymorphic microsatellite loci. High haplotype diversity and low measures of nucleotide diversities including a significantly negative Tajima's D indicate that C. ohridella has experienced rapid population expansion during its dispersal across Europe. Both mtDNA and microsatellites show a reduction in genetic diversity of C. ohridella populations sampled from artificial habitats (e.g. planted trees in public parks, gardens, along roads in urban or sub-urban areas) across Europe compared with C. ohridella sampled in natural stands of horse-chestnuts in the southern Balkans. These findings suggest that European populations of C. ohridella may indeed derive from the southern Balkans.

Differences in duplication age distributions between human GPCRs and their downstream genes from a network prospective

BackgroundHow gene duplication has influenced the evolution of gene networks is one of the core problems in evolution. Current duplication-divergence theories generally suggested that genes on the periphery of the networks were preferentially retained after gene duplication. However, previous studies were mostly based on gene networks in invertebrate species, and they had the inherent shortcoming of not being able to provide information on how the duplication-divergence process proceeded along the time axis during major speciation events.ResultsIn this study, we constructed a model system consisting of human G protein-coupled receptors (GPCRs) and their downstream genes in the GPCR pathways. These two groups of genes offered a natural partition of genes in the peripheral and the backbone layers of the network. Analysis of the age distributions of the duplication events in human GPCRs and "downstream genes" gene families indicated that they both experienced an explosive expansion at the time of early vertebrate emergence. However, we found only GPCR families saw a continued expansion after early vertebrates, mostly prominently in several small subfamilies of GPCRs involved in immune responses and sensory responses.ConclusionIn general, in the human GPCR model system, we found that the position of a gene in the gene networks has significant influences on the likelihood of fixation of its duplicates. However, for a super gene family, the influence was not uniform among subfamilies. For super families, such as GPCRs, whose gene basis of expression diversity was well established at early vertebrates, continued expansions were mostly prominent in particular small subfamilies mainly involved in lineage-specific functions.

Shell explosion and core expansion of xenon clusters irradiated with intense femtosecond soft x-ray pulses

The disintegration mechanisms for xenon clusters in intense femtosecond soft x-ray pulses from the FLASH free electron laser are investigated. The clusters are irradiated at a wavelength of λ = 13.7 nm (hν = 90.5 eV) and power densities of 5 × 1014 W cm−2. During the 10 fs pulse the Xe clusters are transformed into a highly excited, multiply charged nanoplasma. Simulating the ion kinetic energies in an electrostatic model suggests that highly charged ions explode off the surface due to Coulomb repulsion while the inner core expands in a hydrodynamic expansion. The current results yield evidence for efficient ionization of the clusters in addition to direct multistep photoemission.

232 Explosive Expansion of HIV and associated risk factors among Male and Hijra Sex Workers in Sindh, Pakistan

232 Explosive Expansion of HIV and associated risk factors among Male and Hijra Sex Workers in Sindh, Pakistan

ICT expansion and the digital divide in democratic freedoms: An analysis of the impact of ICT expansion, education and ICT filtering on democracy

In recent years, several case studies have appeared on how mobile telephones, SMS and the Internet had an impact on political activities. It has been widely argued that information and communication technology (ICT) is influencing democracy all over the world. However, few studies provide any analysis of how ICT expansion correlates with measures of democracy. In this paper, we investigate the relationship between the global expansion of ICT and the level of democracy within nations. We analyze archival data on 133 countries from 1995 to 2003, which was the period-of-time of explosive ICT expansion. Some important findings of our study are: (a) there is a growing digital divide in democratic freedoms among countries; (b) in spite of rapid ICT expansion in some countries, Internet filtering is having a significant impact on democratic freedoms.

The Art of Pimping

in 1989. As he defined it, pimping occurs when an attending physician (the Pimper) poses a series of difficult questions to a resident or medical student (the Pimpee). Pimping usually occurs in settings such as “morning report” or “attending rounds,” in which trainees at various levels convene with a faculty member to review patients currently under their care. Among surgeons, pimping may occur when students and residents are a captive audience observing a patient undergoing an operation. Brancati described the origins of the term, which date back to 17th-century London. Koch’s series of “Pumpfrage” (pimp questions) were used on his rounds in the 19th century. The practice migrated to North America in the 20th century and was documented by Flexner while observing Osler making rounds at Johns Hopkins. Brancati outlined suggestions for attending physicians to further hone their pimping skills and methods for students to defend themselves from it. He posited that the art of pimping would disappear in the future with increased specialization and educational reorganization. This Commentary revisits the art of pimping 20 years later and provides an update for faculty members and students alike on modern methods in this important skill. Pimping is indeed alive and well within academic medicine for several reasons. First, the basic structure of medical teaching has not changed. Ross and Detsky have described the teaching services at 2 academic hospitals on both sides of the Canada/US border. Students and residents still work up patients and report to attending physicians as much in 2009 as they did in the last half of the 20th century. Faculty still meet with smallto medium-sized groups of medical students and residents and use interactive methods that somewhat resemble Socratic techniques. Second, the power relationship between teacher and student still exists and likely always will, because the teacher has more content knowledge and is responsible for evaluating the students. Pimping reinforces that power relationship because the teacher usually controls the questions. The teacher likely knows the answers while the students may or may not. A historical example of the effect of this phenomenon was described by Ausiello in a brief biography of Their. When Their was chair of medicine at Yale, a resident once fainted from anxiety prior to a case presentation. This experience resulted in giving Thier the nickname “Syncope Sam.” The third reason pimping has flourished is the explosive expansion of the knowledge base in clinical medicine.

Dopamine and Aging: Intersecting Facets

Aging encompasses life itself so understanding requires frameworks that forge unity amidst complexity. The free radical theory of aging is one example. The original focus on damage was augmented recently by appreciation that reactive oxygen and nitrogen species are essential to normal signaling and cell function. This paradigm is currently undergoing an explosive expansion fueled by the discovery that regulatory organization is a merry-go-round of redox cycling seamlessly fused to endogenous clocks. This might best be described as an "Electroplasmic Cycle." This is certainly applicable to dopaminergic neurons with their exceptional metabolic, electrical and rhythmic properties. Here I review normal aging of dopamine systems to highlight them as a valuable model. I then examine the possible integration of free radical and ion channel theories of aging. Finally, I incorporate clocks and explore the multifaceted implications of electroplasmic cycles with special emphasis on dopamine.

The Art of Listening

443 IAND A GROUP OF MY FRIENDS have, for about thirty-one years, been trying to develop and expand and improve a system for people relating to each other helpfully. For the last eleven years our efforts have gone beyond the city of Seattle and in that time have spread to nearly every state in the Union, nearly every large city in the United States, most Canadian provinces, and about thirty-eight other countries. We’ve had an explosive expansion. Our understanding SOMEONE MUST LISTEN If we were to encapsulate what we have learned to do in a sentence or two—and there’s much more, there are many complicated applications that come from it—it is to explain to people that what they are trying to do all the time, this trying to be listened to, is a very profound process. It will have profound results if it ever gets a chance to operate and it will operate, if they will take turns. They need to just take turns, and agree, “Yes, I will listen to you and really pay attention to you for a while, if you will give me a chance to do the same thing later on.” We call that “Co-Counseling.” The awkward word “counseling” meant “giving advice” to most people when we first started using it, but it has now come to have a good deal of the meaning we’ve used for it in the intervening thirty-one years, which does not mean “giving advice” at all, but basically listening and paying attention. This inherent process that we’re all equipped to use has been, in general, frustrated, simply because it takes another person outside of ourselves really paying attention while we talk and think about ourselves, and re-experience the distresses that we have accumulated, for it to work.

A New Forum for Cardiovascular Imaging Research

The field of cardiovascular imaging is witnessing an explosive expansion of its armamentarium of noninvasive technologies capable of providing detailed information about the structure and function of the heart and vasculature. Many of these technologies are integrating (eg, positron emission tomography and computed tomography, positron emission tomography and magnetic resonance imaging), compounding the unique strengths of the component technologies to achieve improved diagnosis of disease and better patient care. In addition, the miniaturization of imaging devices with dramatic increases in sensitivity and spatial resolution, coupled with the development of quantitative targeted imaging approaches for evaluating physiology and pathophysiology at the cellular and molecular levels, provides a unique platform for a new era in diagnostic imaging. The crucial role of imaging in early phenotyping of disease, risk definition, management guidance, and outcome assessment is expanding rapidly in ways previously thought unrealistic. These technological advances have ignited an unprecedented convergence of disciplines (cardiology, radiology, nuclear medicine, molecular biology, medical physics, and chemistry) that together are promoting innovation and new clinical applications in cardiovascular imaging. The dramatic growth …

Pure-tin microdroplets irradiated with double laser pulses for efficient and minimum-mass extreme-ultraviolet light source production

Laser-driven expansion of pure-tin microdroplets was demonstrated to produce an efficient and low-debris extreme-ultraviolet (EUV) light source. The pre-expansion is indispensable for resolving the considerable mismatch between the optimal laser spot diameter (∼300μm) and the diameter (∼20μm) of microdroplets containing the minimum-mass Sn fuel for generating the required EUV radiant energy (∼10mJ/pulse). Explosive expansion of microdroplets was attained by using a laser prepulse, whose intensity was at least 3×1011W∕cm2. The expanded microdroplet was irradiated with a CO2 laser pulse to generate EUV light. A combination of low density and long-scale length of the expanded microdroplet leads to a higher EUV energy conversion efficiency (4%) than that (2.5%) obtained from planar Sn targets irradiated by a single CO2 laser pulse. This scheme can be used to produce a practical EUV light source system.

Symposium 5: Exploiting Distance Learning Methods and Multimedia-enhanced instructional content to support IT Curricula in Greek Technological Educational Institutes

Various instructional strategies and material are at the disposal of the designers and tutors of online distance courses. However, in order to be effective, instructional interaction must exhibit some specific characteristics. Designers and tutors have to make (and change) decisions related to the selection and sequencing of the instructional material, specify when and how to cover students'needs during the phase of practicing specific skills and understand when to respond to students'difficulties about the subject matter. They also have to be aware (during the stages of the design of an online, distance-course) of the theory and practice already established in the context of distance tutoring. Standardization of expected learning outcomes in computer science departments has been acknowledged by internationally recognized organizations such as the ACM or the IEEE. According to the ACM/IEEE Computing curricula, "computer science students need to be able to develop conceptual and physical models, determine methods appropriate for providing efficient solutions to a given problem, and be able to select and implement appropriate solutions that reflect suitable constraints, including scalability and usability". The need for standardization and adoption of such principles has also emerged in the case of Greek Technological Education Institutes. Multimedia support also arises as an interesting challenge in modern academic education schemes. An overall support of these principles, as well as the description and evaluation of a multimedia enhanced teaching methodology has been part of our research considerations. An important constraint factor of Technological Education in Greece is the low ratio of the permanent teaching staff in respect to the continuously growing number of students. In addition, the ongoing explosive expansion of the Greek higher education has further aggravated the situation. Hence, the driving forces behind our efforts have been the need for standardization and co-operation, the limited time frame, and the lack of human teaching resources. Unfortunately, traditional instructional design models generally tend to be linear, step by step guides directing the tutor through a series of necessary stages. Therefore, an "ambitious", non-prescriptive, combined Content - Instruction and Tutor - Learner Centred Approach (COIN_TULE) must be applied. The suggested approach is based on activities and task sets emerging from published research results and practitioners'experience about the natures of learning, instruction and the subject matter. More precisely, we try to explore, examine and capture the relationship between Content and Instruction (COIN-relationship) and the relationship between Tutor and Learner (TULE-relationship). Such a work forms a basis for the extraction of useful characteristics that are incorporated into a methodological framework. The major advantage of this approach is that the Learner is put at the centre, which, not only improves understanding of the target audience, but also emphasises on the definition of course goals and learning objectives, the compilation of a detailed description of the content to be included, etc. In this paper we present a methodological framework for supporting the combinatory use of distance learning techniques, based on a mixed COIN_TULE and multimedia enhanced approach. At first, we briefly formulate the problem and describe the decisions which direct our choices. We explain the planning and design of our framework, presenting the sub-tasks related within the framework in more detail. Finally, we discuss evaluation of the learning experiments we have conducted, along with interesting outcomes and directions for future work.