Time-It's time for a change

Since the 1970's, the scientific field of model-based performance and dependability evaluation has been flourishing. Starting with breakthroughs in the area of closed queueing networks in the 1970's, the 1980's brought new results on state-based methods, such as those for stochastic Petri nets and matrix-geometric methods, whereas the 1990's introduced process algebra-type models. Since the turn of the century, techniques for stochastic model checking are being introduced, to name just a few major developments. The applicability of all these techniques has been boosted enormously through Moore's law; these days, stochastic models with tens of millions of states can easily be dealt with on a standard desktop or laptop computer. A dozen or so dedicated conferences serve the scientific field, as well as a number of scientific journals. However, for the field as a whole to make progress, it is important to step back, and to consider how all these as-such important developments have really changed the way computer and communication systems are being designed and operated. The answer to this question is most probable rather disappointing. I do observe a rather strong discrepancy between what is being published in top conferences and journals, and what is being used in real practice. Blaming industry for this would be too easy a way out. Currently, we do not see model-based performance and dependability evaluation as key step in the design process for new computer and communication systems. Moreover, in the exceptional cases that we do see performance and dependability evaluation being part of a design practice, the employed techniques are not the ones referred to above, but instead, depending on the application area, techniques like discrete-event simulation on the basis of hand-crafted simulation programs (communication protocols), or techniques based on (non-stochastic) timed-automata or timeless behavioral models (embedded systems). In all these cases, however, th- e scalability of the employed methods, also for discrete-event simulation, forms a limiting factor. Still, industry is serving the world with ever better, faster and more impressive computing machinery and software! What went wrong? When and why did ?our field? land on a side track? In this presentation I will argue that it is probably time for a change, for a change toward a new way of looking at performance and dependability models and evaluation of computer and communication systems, a way that is, if you like, closer to the way physicists deal with very large scale systems, by applying different type of abstractions. In particular, I will argue that computer scientist should ?stop counting things?. Instead, a more fluid way of thinking about system behavior is deemed to be necessary to be able to evaluate the performance and dependability of the next generation of very large scale omnipresent systems. First successes of such new approaches have recently been reported. Will be witness a paradigm shift in the years to come

Relaxation of Spin Polarized 3^3He in Mixtures of 3^3He and 4^4He Below the 4^4He Lambda Point

We report the first study of the depolarization behavior of spin polarized 3He in a mixture of 3He-4He at a temperature below the 4He Lambda point in a deuterated TetraPhenyl Butadiene-doped deuterated PolyStyrene (dTPB-dPS) coated acrylic cell. In our experiment the measured 3He relaxation time is due to the convolution of the 3He longitudinal relaxation time, T1, and the diffusion time constant of 3He in superfluid 4He since depolarization takes place on the walls. We have obtained a 3He relaxation time ~3000 seconds at a temperature around 1.9K. We have shown that it's possible to achieve values of wall depolarization probability on the order of (1-2)x10^-7 for polarized 3He in the superfluid 4He from a dTPB-dPS coated acrylic surface.Comment: The Model used to interpret the data has been change

The official student newspaper of the University of Alaska Southeast - Juneau

Bishop Kenny shares Middle East experiences -- New classrooms proposed for UAS Campus -- Honors Brass Quintet offers workshop, concerts -- If you Don't Like It; Get Involved and Change It! -- Child goes for Guinness -- Correction -- Added stress of assessment is well worth the improvement in quality of student writing at UAS -- It's Time For Commitment -- Write a letter, join the staff, or quit your bitching -- UAS Men's And Women's Teams Win -- Giving the gift of music: Boxed sets offer treat for collectors -- Auke Lake campus to get bus stop shelter in 1991 -- Clubs on campus seek active members -- Student Art Show At Egan Library -- Sobriety: a new look at an old problem -- Local poet

Sequential Change-point Detection for Binomial Time Series with Exogenous Variables

Sequential change-point detection for time series enables us to sequentially check the hypothesis that the model still holds as more and more data are observed. It's widely used in data monitoring in practice. Meanwhile, binomial time series, which depicts independent binary individual behaviors within a group when the individual behaviors are dependent on past observations of the whole group, is an important type of model in practice but hasn't been developed well. We first propose a Binomial AR($1$) model, and then consider a method for sequential change-point detection for the Binomial AR(1)

Time kink: modeling change of metric signature

The model of a signature change of a metric from the Lorenztian to Euclidean one with the use of a time dependent kink as $g_{00}$ component of the metric is considered. The metric which describes the continuous change of the signature of this type on a hypersurface is constructed and corresponding Einstein equations are solved in both regions of the space-time. The discontinuities of the Einstein tensor components on the hypersurface are discussed as well as junction conditions for the parameters of the solutions. Additionally, the properties of simple cosmological model are discussed in the model, the presence of an inflation in the model is demonstrated as a consequence of the signature change without any additional fields need. The possible appearance of this type of solution for the metric in the form of the scalar field in the framework of the Einstein-Cartan gravity is described. The Lagrangian for that field and it's properties are obtained as well as a time dependent potential of the field which separate the Lorentzian and Euclidean regions of the space-time

Statistically Significant Detection of Linguistic Change

We propose a new computational approach for tracking and detecting statistically significant linguistic shifts in the meaning and usage of words. Such linguistic shifts are especially prevalent on the Internet, where the rapid exchange of ideas can quickly change a word's meaning. Our meta-analysis approach constructs property time series of word usage, and then uses statistically sound change point detection algorithms to identify significant linguistic shifts. We consider and analyze three approaches of increasing complexity to generate such linguistic property time series, the culmination of which uses distributional characteristics inferred from word co-occurrences. Using recently proposed deep neural language models, we first train vector representations of words for each time period. Second, we warp the vector spaces into one unified coordinate system. Finally, we construct a distance-based distributional time series for each word to track it's linguistic displacement over time. We demonstrate that our approach is scalable by tracking linguistic change across years of micro-blogging using Twitter, a decade of product reviews using a corpus of movie reviews from Amazon, and a century of written books using the Google Book-ngrams. Our analysis reveals interesting patterns of language usage change commensurate with each medium.Comment: 11 pages, 7 figures, 4 table

Directional mobility of debt ratings

In this paper we describe a method to decompose a well-known measure of debt ratings mobility into it's directional components. We show, using sovereign debt ratings as an example, that this directional decomposition allows us to better understand the underlying characteristics of debt ratings migration and, for the case of the data set used, that the standard Markov chain model is not homogeneous in either the time or cross-sectional dimensions. We find that the directional decomposition also allows us to sign the change in quality of debt over time and across sub-groups of the population

An Overview of Mobile Ad Hoc Networks for the Existing Protocols and Applications

Mobile Ad Hoc Network (MANET) is a collection of two or more devices or nodes or terminals with wireless communications and networking capability that communicate with each other without the aid of any centralized administrator also the wireless nodes that can dynamically form a network to exchange information without using any existing fixed network infrastructure. And it's an autonomous system in which mobile hosts connected by wireless links are free to be dynamically and some time act as routers at the same time, and we discuss in this paper the distinct characteristics of traditional wired networks, including network configuration may change at any time, there is no direction or limit the movement and so on, and thus needed a new optional path Agreement (Routing Protocol) to identify nodes for these actions communicate with each other path, An ideal choice way the agreement should not only be able to find the right path, and the Ad Hoc Network must be able to adapt to changing network of this type at any time. and we talk in details in this paper all the information of Mobile Ad Hoc Network which include the History of ad hoc, wireless ad hoc, wireless mobile approaches and types of mobile ad Hoc networks, and then we present more than 13 types of the routing Ad Hoc Networks protocols have been proposed. In this paper, the more representative of routing protocols, analysis of individual characteristics and advantages and disadvantages to collate and compare, and present the all applications or the Possible Service of Ad Hoc Networks.Comment: 24 Pages, JGraph-Hoc Journa

Purchasing a good from one‘s own business

The world is changing by the unbeatable pace, technology progresses, globalization is taking place and a man is stuck in that vicious cycle. In order to cope up with change man needs to learn constantly, othenvise he is doomed. The environment has changed drastically from the time of Revelation and Prophethood. As the consequence of the drastic change new questions arose in all the aspects of human life, no matter of lifestyle, being it's Islamic or othenvise. The Shariah rules have always been absolute and they are being harder and harder to apply and interpret for a layma