bluuebunny/crossref_metadata_2025 huggingface dataset:
Compilation and evaluation of gas-phase diffusion coefficients of reactive trace gases in the atmosphere: volume 2. Organic compounds and Knudsen numbers for gas uptake calculations
Authors: Tang M. J. , Shiraiwa M. , Pöschl U. , Cox R. A. , Kalberer M.
Published: February 2015

Abstract. Diffusion of organic vapours to the surface of aerosol or cloud particles is an important step for the formation and transformation of atmospheric particles. So far, however, a database of gas phase diffusion coefficients for organic compounds of atmospheric interest has not been available. In this work we have compiled and evaluated gas phase diffusivities (pressure-independent diffusion coefficients) of organic compounds reported by previous experimental studies, and we compare the measurement data to estimates obtained with Fuller's semi-empirical method. The difference between measured and estimated diffusivities are mostly < 10%. With regard to gas-particle interactions, different gas molecules, including both organic and inorganic compounds, exhibit similar Knudsen numbers (Kn) although their gas phase diffusivities may vary over a wide range. Knudsen numbers of gases with unknown diffusivity can be approximated by a simple function of particle diameter and pressure and can be used to characterize the influence of diffusion on gas uptake by aerosol or cloud particles. We use a kinetic multi-layer model of gas-particle interaction to illustrate the effects of gas phase diffusion on the condensation of organic compounds with different volatilities. The results show that gas-phase diffusion can play a major role in determining the growth of secondary organic aerosol particles by condensation of low-volatility organic vapours.
The white-light humidified optical particle spectrometer (WHOPS) – a novel airborne system to characterize aerosol hygroscopicity
Authors: Rosati B. , Wehrle G. , Gysel M. , Zieger P. , Baltensperger U. , Weingartner E.
Published: February 2015

Abstract. Aerosol particles experience hygroscopic growth at enhanced relative humidity (RH), which leads to changes in their optical properties. We developed the white-light humidified optical particle spectrometer (WHOPS), a new instrument to investigate the particles' hygroscopic growth. Here we present a detailed technical description and characterization of the WHOPS in laboratory and field experiments. The WHOPS consists of a differential mobility analyzer, a humidifier/bypass and a white-light aerosol spectrometer (WELAS) connected in series to provide fast measurements of particle hygroscopicity at subsaturated RH and optical properties on airborne platforms. The WELAS employs a white-light source to minimize ambiguities in the optical particle sizing. In contrast to other hygroscopicity instruments, the WHOPS retrieves information of relatively large particles (i.e., diameter D > 280 nm), therefore investigating the more optically relevant size ranges. The effective index of refraction of the dry particles is retrieved from the optical diameter measured for size-selected aerosol samples with a well-defined dry mobility diameter. The data analysis approach for the optical sizing and retrieval of the index of refraction was extensively tested in laboratory experiments with polystyrene latex size standards and ammonium sulfate particles of different diameters. The hygroscopic growth factor (GF) distribution and aerosol mixing state is inferred from the optical size distribution measured for the size-selected and humidified aerosol sample. Laboratory experiments with pure ammonium sulfate particles revealed good agreement with Köhler theory (mean bias of ~3% and maximal deviation of 8% for GFs at RH = 95%). During first airborne measurements in the Netherlands, GFs (mean value of the GF distribution) at RH = 95% between 1.79 and 2.43 with a median of 2.02 were observed for particles with a dry diameter of 500 nm. This corresponds to hygroscopicity parameters (κ) between 0.25 and 0.75 with a median of 0.38. The GF distributions indicate externally mixed particles covering the whole range of GFs between ~1.0 and 3.0. On average, ~74% of the 500 nm particles had GFs > 1.5, ~15% had GF < 1.1 and the remaining ~1% showed values of 1.1 < GF < 1.5. The more hygroscopic mode sometimes peaked at GF > 2, indicating influence of sea-salt particles, consistent with previous ground-based particle hygroscopicity measurements in this area. The mean dry effective index of refraction for 500 nm particles was found to be rather constant with a value of 1.42 ± 0.04 (mean ± 1SD).
Altitude misestimation caused by the Vaisala RS80 pressure bias and its impact on meteorological profiles
Authors: Inai Y. , Shiotani M. , Fujiwara M. , Hasebe F. , Vömel H.
Published: February 2015

Abstract. Previous research has found that conventional radiosondes containing a traditional pressure sensor can be subject to a pressure bias, particularly in the stratosphere. This study examines this pressure bias, and the resulting altitude misestimation, and considers its impact on temperature, ozone, and water vapor profiles, using data obtained between December 2003 and January 2010 during the Soundings of Ozone and Water in the Equatorial Region (SOWER) campaigns. The observation package consisted of a radiosonde (Vaisala RS80), ozone and water vapor sondes, and a global positioning system (GPS) sensor. More than 30 soundings are used in this study. As GPS height data are thought to be highly accurate, they can be used to calculate pressure. The RS80 pressure bias in the tropical stratosphere was estimated to be −0.4 ± 0.2 hPa (1σ) between 20 and 30 km. As this pressure bias is negative throughout the stratosphere, it leads to altitude misestimation when heights are calculated, as this is usually achieved using the hydrostatics equation. We estimated the error in geometric height to be 42 ± 24, 110 ± 39, and 240 ± 90 m (1σ) at 20, 25, and 30 km, respectively. Because of the altitude misestimation, we saw some differences in observation parameters having a vertical gradient. For the temperature profiles, the differences were approximately −0.2 ± 0.2, −0.2 ± 0.4, and −0.3 ± 0.8 K (1σ) at 20, 25, and 30 km, respectively. For the ozone profiles, there was a maximum of ozone partial pressure at around 27 km. Therefore, the differences do not monotonically increase with increasing altitude, and they are estimated to be −1.9 ± 1.6, −0.7 ± 1.0, and 3.1 ± 2.2% (1σ) at 20, 25, and 30 km, respectively. For the water vapor profiles, as there are minima and maxima associated with the stratospheric tape recorder signal, the differences are affected by the phase of the tape recorder. If we align water vapor profiles using a water vapor minimum, the differences are estimated to be −2.7 ± 8.1% at 0.5 km and 1.5 ± 1.0% (1σ) at 4 km above the water vapor minimum around the cold point tropopause. These biases in the meteorological soundings obtained using the RS80 may have generated an artificial trend in the meteorological records when radiosondes were changed from the RS80, which had no GPS sensor, to the new ones with a GPS sensor. Therefore, it is important to take these biases into account in climate change studies.
The contribution of tephra constituents during biogenic silica determination: implications for soil and paleoecological studies
Authors: Clymans W. , Barão L. , Van der Putten N. , Wastegård S. , Gísladóttir G. , Björck S. , Moine B. , Struyf E. , Conley D. J.
Published: February 2015

Abstract. Biogenic silica (BSi) is used as a proxy by soil scientists to identify biological effects on the Si cycle and by paleoecologists to study environmental changes. Alkaline extractions are typically used to measure BSi in both terrestrial and aquatic environments. The dissolution properties of volcanic glass in tephra deposits and their nano-crystalline weathering products are hypothesized to overlap those of BSi, however, data to support this behavior are lacking. The understanding that the Si-bearing fractions that dissolve in alkaline media (SiAlk) do not necessarily correspond to BSi, question the applicability of BSi as a proxy. Here, analysis of 15 samples reported as tephra-containing allows us to reject the hypothesis that tephra constituents produce an identical dissolution signal to that of BSi during alkaline extraction. We found that dissolution of volcanic glass shards is incomplete during alkaline dissolution. Simultaneous measurement of Al and Si used here during alkaline dissolution provides an important parameter to enable us to separate glass shard dissolution from dissolution of BSi and other Si-bearing fractions. The contribution from volcanic glass shard (between 0.2–4 wt.% SiO2), the main constituent of distal tephra, during alkaline dissolution can be substantial depending on the total SiAlk. Hence, soils and lake sediments with low BSi concentrations are highly sensitive to the additional dissolution from tephra constituents and its weathering products. We advise evaluation of the potential for volcanic or other non-biogenic contributions for all types of studies using BSi as an environmental proxy.
Sediment CO2 efflux from cleared and intact temperate mangroves and tidal flats
Authors: Bulmer R. H. , Schwendenmann L. , Lundquist C. J.
Published: February 2015

Abstract. Temperate mangroves in Southern Australia and New Zealand have been increasing in area over the past 50 years, whereas tropical mangroves have declined by 30–50% over a similar time frame. Tropical mangroves are understood to be an important carbon sink and carbon dioxide (CO2) emissions following clearance are estimated to be comparable or greater than CO2 emissions following the clearance of many terrestrial forest systems. Recreational and amenity values or perceived loss of other estuarine habitats due to expanding temperate mangrove forests have resulted in clearing of temperate mangroves. In this study, we investigated the impact of temperate mangrove clearance on CO2 efflux from the sediment to the atmosphere along with a range of other biotic and abiotic factors. Significantly higher CO2 efflux rates were measured in cleared (1.34 ± 0.46 μmol m2 s-1) and intact mangrove sites (2.31 ± 0.72 μmol m2 s-1) than in tidal flats (-0.23 ± 0.27 μmol m2 s-1). Site and sediment characteristics such as sediment carbon and nitrogen concentration, chlorophyll α concentration, grain size, mangrove height, macrofaunal abundance, sediment temperature and moisture were strongly correlated with sediment CO2 efflux. Our results suggest that carbon stored within temperate mangrove sediment is released over a period of years to decades after mangrove clearance. CO2 efflux from intact and cleared temperate mangroves was found to be comparable to rates observed in the tropics. Disturbance of the surface biofilm resulted in elevated CO2 efflux across all habitats, suggesting the important role of surface biofilm communities in mediating CO2 efflux.
A conceptual socio-hydrological model of the co-evolution of humans and water: case study of the Tarim River basin, western China
Authors: Liu D. , Tian F. , Lin M. , Sivapalan M.
Published: February 2015

Abstract. The complex interactions and feedbacks between humans and water are critically important issues but remain poorly understood in the newly proposed discipline of socio-hydrology (Sivapalan et al., 2012). An exploratory model with the appropriate level of simplification can be valuable for improving our understanding of the co-evolution and self-organization of socio-hydrological systems driven by interactions and feedbacks operating at different scales. In this study, a simplified conceptual socio-hydrological model based on logistic growth curves is developed for the Tarim River basin in western China and is used to illustrate the explanatory power of such a co-evolutionary model. The study area is the main stream of the Tarim River, which is divided into two modeling units. The socio-hydrological system is composed of four sub-systems, i.e., the hydrological, ecological, economic, and social sub-systems. In each modeling unit, the hydrological equation focusing on water balance is coupled to the other three evolutionary equations to represent the dynamics of the social sub-system (denoted by population), the economic sub-system (denoted by irrigated crop area ratio), and the ecological sub-system (denoted by natural vegetation cover), each of which is expressed in terms of a logistic growth curve. Four feedback loops are identified to represent the complex interactions among different sub-systems and different spatial units, of which two are inner loops occurring within each separate unit and the other two are outer loops linking the two modeling units. The feedback mechanisms are incorporated into the constitutive relations for model parameters, i.e., the colonization and mortality rates in the logistic growth curves that are jointly determined by the state variables of all sub-systems. The co-evolution of the Tarim socio-hydrological system is then analyzed with this conceptual model to gain insights into the overall system dynamics and its sensitivity to the external drivers and internal system variables. The results show a costly pendulum swing between a balanced distribution of socio-economic and natural ecologic resources among the upper and lower reaches and a highly skewed distribution towards the upper reach. This evolution is principally driven by the attitudinal changes occurring within water resources management policies that reflect the evolving community awareness of society to concerns regarding the ecology and environment.
Increased Dose Single-agent Gemcitabine in Platinum-taxane Resistant Metastatic Ovarian Cancer
Authors: Kodaz Hilmi , Hacibekiroglu Ilhan , Turkmen Esma , Erdogan Bulent , Elpen Cagnur , Uzunoglu Sernaz , Cicin Irfan
Published: February 2015

Background

In platinum-taxane resistant epithelial ovarian cancer (EOC), we aimed to determine the effectiveness.

Patients and Methods

Between 2004 and 2013, patients afflicted with platinum-taxane resistant EOC and who were administered a 30-minute i.v. infusion of single-agent gemcitabine at a dose of 1,250 mg/m2 on the 1st, 8th and 15th days, every 28 days, were examined retrospectively.

Results

Twenty-six patients with platinum-taxane resistant EOC were included in the study. The overall survival (OS) was 48 months. The median survival after becoming platinum-taxane resistant was 16 months for the study population. Median time to progression (TTP) and median survival after becoming platinum-taxane resistant for patients who received second-line treatment were 3.3 months and 16 months, respectively; for patients who received third-line treatment with gemcitabine, these were 3.7 months and 19 months, respectively. Administration of gemcitabine as second- and third-line chemotherapy in platinum-taxane resistant EOC, provides similar TTP and OS outcomes (p = 0.4, p = 0.9) with a similar response and toxicity rate.

Conclusions

Second- and third-line gemcitabine at a dose of 1,250 mg/m2 on days 1, 8 and 15 every 28 days as a 30-minute i.v. infusion in platinum-taxane resistant EOC is an effective treatment option with a tolerable and manageable toxicity.
The Ethical Importance of the Beautiful:
Authors: LEUNG WING SZE
Published: February 2015

Recent scholars interested in Wordsworth's relation to the empiricist tradition disagree on the extent to which his notion of the imagination resembles what Hume meant by “association.” This article examines this debate in the context of the earlier books of The Prelude (1805), as a way to explore how Wordsworth's conception of the beautiful contained therein both exhibits fundamental characteristics of and diverges from Hume's empiricism. I first argue that despite certain similarities, the mechanism of association fails to adequately explain Wordsworth's imaginary activities. I then show how Wordsworth's conception of the imagination enabled him to reconceive Hume's empiricist aesthetics. I argue that while incorporating the language of empiricism, Wordsworth's account of the beauty of nature also demonstrated its originality. Whereas Hume conceived of the aesthetic feeling of the beautiful as solely a passive response to the utility of natural objects, Wordsworth perceived it as an expression of love and respect for nature's moral standing—an outlook that played a vital role in developing his moral sympathy.
Investigación y publicaciones de estudiantes de grado y posgrado
Authors: Moncada Godoy German
Published: February 2015

DOI: http://dx.doi.org/10.5377/pc.v4i0.1857 Revista Portal de la Ciencia, No. 4, julio 2013: 3-13
Determination of pKa Values for Acrylic, Methacrylic and Itaconic Acids by 1H and 13C NMR in Deuterated Water
Authors: Ibarra-Montaño Emma Lilia , Rodríguez-Laguna Norma , Sánchez-Hernández Aníbal , Rojas-Hernández Alberto
Published: February 2015

Acrylic, methacrylic and itaconic acids have Brønsted acidity given by carboxylic groups, and they are extensively used in polymerization for modification of several soft-mater materials. By this reason it is important to propose better characterization studies and alternatives to obtain more of their physicochemical properties. In this work the pKa values of these acids are obtained by adjusting NMR chemical shifts for hydrogen and carbon nuclei as a function of pH with program HYPNMR, and compared with those obtained by potentiometric and conductometric titrations.
Effects of Metal Ions on H2 Generation during Photolysis of Suspended TiO2 in Aqueous Systems
Authors: Dey G.R.
Published: February 2015

Nowadays, photocatalysis is being applied as a promising technique for decontamination, purification, deodorization, etc. of polluted air and wastewaters. This technique attempts also to generate renewable and non-polluting fuels utilizing various carbon and hydrogen sources. In this context, studies on photo-catalytic generation of H2 using 0.1% w/v TiO2 photo catalyst as a suspension in water was carried out using 350 nm light. This was explored further in presence of various metal ions such as Ag+, Cu2+, Fe2+, Au3+ and V5+ at different ambient such as air and CO2, in presence of a hole scavenger (2-propanol and formic acid). H2 yields in CO2-purged systems as analyzed in GC-TCD were reasonably higher, and increased further when metal ions were added into the systems. Based on H2 yields, HCOOH was found to be a more supportive hole scavenger as compared to 2-propanol in metal ions containing systems. Besides the formation of low to high concentrations of various gaseous products, nanoparticles of gold, silver and copper were also observed as photolysis products. This indicated that the presence of both reduced metal ions and their in-situ generated nanoparticles at various stages either in the free/unbound and/or associated with TiO2 photocatalyst in aqueous systems, together play a significant role in enhancing the H2 yields.
Hox genes control vertebrate body elongation by collinear Wnt repression
Authors: Denans Nicolas , Iimura Tadahiro , Pourquié Olivier
Published: February 2015

In vertebrates, the total number of vertebrae is precisely defined. Vertebrae derive from embryonic somites that are continuously produced posteriorly from the presomitic mesoderm (PSM) during body formation. We show that in the chicken embryo, activation of posterior Hox genes (paralogs 9–13) in the tail-bud correlates with the slowing down of axis elongation. Our data indicate that a subset of progressively more posterior Hox genes, which are collinearly activated in vertebral precursors, repress Wnt activity with increasing strength. This leads to a graded repression of the Brachyury/T transcription factor, reducing mesoderm ingression and slowing down the elongation process. Due to the continuation of somite formation, this mechanism leads to the progressive reduction of PSM size. This ultimately brings the retinoic acid (RA)-producing segmented region in close vicinity to the tail bud, potentially accounting for the termination of segmentation and axis elongation.
Angiopoietin-like proteins stimulate HSPC development through interaction with notch receptor signaling
Authors: Lin Michelle I , Price Emily N , Boatman Sonja , Hagedorn Elliott J , Trompouki Eirini , Satishchandran Sruthi , Carspecken Charles W , Uong Audrey , DiBiase Anthony , Yang Song , Canver Matthew C , Dahlberg Ann , Lu Zhigang , Zhang Cheng Cheng , Orkin Stuart H , Bernstein Irwin D , Aster Jon C , White Richard M , Zon Leonard I
Published: February 2015

Angiopoietin-like proteins (angptls) are capable of ex vivo expansion of mouse and human hematopoietic stem and progenitor cells (HSPCs). Despite this intriguing ability, their mechanism is unknown. In this study, we show that angptl2 overexpression is sufficient to expand definitive HSPCs in zebrafish embryos. Angptl1/2 are required for definitive hematopoiesis and vascular specification of the hemogenic endothelium. The loss-of-function phenotype is reminiscent of the notch mutant mindbomb (mib), and a strong genetic interaction occurs between angptls and notch. Overexpressing angptl2 rescues mib while overexpressing notch rescues angptl1/2 morphants. Gene expression studies in ANGPTL2-stimulated CD34+ cells showed a strong MYC activation signature and myc overexpression in angptl1/2 morphants or mib restored HSPCs formation. ANGPTL2 can increase NOTCH activation in cultured cells and ANGPTL receptor interacted with NOTCH to regulate NOTCH cleavage. Together our data provide insight to the angptl-mediated notch activation through receptor interaction and subsequent activation of myc targets.
Serotonergic neurons signal reward and punishment on multiple timescales
Authors: Cohen Jeremiah Y , Amoroso Mackenzie W , Uchida Naoshige
Published: February 2015

Serotonin's function in the brain is unclear. One challenge in testing the numerous hypotheses about serotonin's function has been observing the activity of identified serotonergic neurons in animals engaged in behavioral tasks. We recorded the activity of dorsal raphe neurons while mice experienced a task in which rewards and punishments varied across blocks of trials. We ‘tagged’ serotonergic neurons with the light-sensitive protein channelrhodopsin-2 and identified them based on their responses to light. We found three main features of serotonergic neuron activity: (1) a large fraction of serotonergic neurons modulated their tonic firing rates over the course of minutes during reward vs punishment blocks; (2) most were phasically excited by punishments; and (3) a subset was phasically excited by reward-predicting cues. By contrast, dopaminergic neurons did not show firing rate changes across blocks of trials. These results suggest that serotonergic neurons signal information about reward and punishment on multiple timescales.
Software Architecture Modeling for User Interfaces
Authors: Coutaz Joëlle
Published: February 2015

The design of software architecture has become an active area of research. Although the ad‐hoc development of software is acceptable for throwaway prototypes, it is now widely recognized that architectural design of complex systems can no longer simply emerge from craft skills. This shared scientific wisdom calls for increased attention in the practice of user interface development.

Current practice in prototyping is not the only motivation for paying attention to architectural design. Emerging interaction techniques are more and more complex.

Software architecture modeling serves two distinct but complementary purposes: the forward design and the reverse design of software structures. On one hand, software architecture modeling guides the development of a future system; on the other hand, it helps to understand the organization of existing code. In both cases, the problem is how to capture architectural knowledge and convey this knowledge to software designers and maintainers in a useful way.

This article reports a state of the art on software architecture modeling for interactive systems. It is structured in the following first, the key concepts from software architecture research and make explicit the design steps that most software designers in HCI tend to blend in a fuzzy way are introduced. Building on general concepts and practice from mainstream software engineering, we then present a comparative analysis of the most significant architecture models developed in HCS is then presented.

The article primarily concentrate on the conceptual aspects of architectural design. The reification of conceptual architectures into implementation architectures which rely on the underlying platform and programming tools, is not addressed.
Business Process Reengineering
Authors: Sneed Harry , Verhoef Chris
Published: February 2015

In this article the fact that the revolution of business process reengineering was not widely implemented, and that many efforts failed is recalled. two major reasons in favor of reengineering old economy information systems are: keeping pace with technology advances and improving business processes. how business processes always traditionally aligned with the technological waves of batch‐oriented information systems and client/server systems, and in the future can align with Web‐based architectures is ultimated. Then how corporations can align their businesses to the information technology of the twenty‐first century: by revolution or by evolution is discussed. When the technological infrastructure is in place, new business processes can emerge. Technology drives business change, and that business (process) reengineering follows software reengineering is stressed.
Component‐Based Systems
Authors: Weide Bruce W.
Published: February 2015

Human‐engineered physical devices such as cars and appliances and computers, as well as naturally occurring physical objects such as forests and galaxies and nerve bundles, are often called “systems.” Both this word and the thinking that underlies it are crucial features of modern software engineering as well. Software systems, however, are purely symbolic entities that have meaning and intellectual interest even without a physical manifestation. Component‐based systems in physical engineering and in software engineering therefore have many common features, yet differ in important and sometimes subtle ways.

The characteristics of component‐based software engineering as currently practiced can be approached from two different perspectives. One explanation is based on the relationship to fundamental principles of system design. In this view, the key features of component‐based software engineering could have developed simply as inevitable consequences of applying general “system thinking” to software systems. Another explanation is based on observing the history of two related branches of software engineering research. In this view, the key features of component‐based software engineering actually have resulted from a melding of the concurrent but curiously separate activities of two communities: advances in software reuse research and common off‐the‐shelf (COTS) component technology, and advances in object‐oriented (OO) technology.

This article begins by exploring the fundamental similarities and differences between component‐based systems in the physical world and those in the software world. It then uses that analysis and a summary of component‐based software research as a basis for understanding the currently unfolding transition from second‐generation to third‐generation OO technology: the integration of component‐based software concepts into modern software practice, which relies on the identification and use of “objects”.
Concurrency in Software Engineering
Authors: Axford Tom
Published: February 2015

Concurrency in software engineering means the collection of techniques and mechanisms that enable a computer program to perform several different tasks simultaneously, or apparently simultaneously. The need for concurrency in software first arose in the very early days of computing. Although early computers were very much slower than modern machines, their peripheral devices (such as paper tape or punched‐card readers for input, and teletypewriters for output) were much slower still, and it was soon recognized that many programs could be made to run very much faster if they did not spend so much time waiting for input/output (I/O). The solution is easy in principle—simply allow I/O transfers to be performed concurrently with each other and with normal computation (i.e., computation involving only the central processor). To achieve this, new features needed to be added to both hardware and software.

Today, such features—concurrency mechanisms, the most important of which are discussed in this article—are commonplace and form a vital part of all modern computer systems. The operating system of any computer (e.g., Windows, UNIX, Linux) makes use of concurrency to enable the user to do several different things simultaneously or to allow many different users to access the computer at the same time. Many operating systems allow a large number of tasks to be run concurrently and the simultaneous use of peripheral devices. The earliest applications of concurrency were in real‐time systems such as operating systems, in which the software must perform actions at times determined by external events.
Interoperability Testing of Integrated Communication Software Systems
Authors: Lee David
Published: February 2015

Interactive graphics offers the software engineer a set of powerful tools for the creation of user interfaces that can convey information in a clear, direct manner. The applications are large in number and highly diverse. The engineer now uses interactive graphics to design and test components for anything from car body frames to silicon chips, the businessperson uses it to look at financial summaries and predictions, the scientist uses it to look at molecules to determine whether they will react, filmmakers use it to create special effects, advertisers use it to animate inanimate objects, and airline pilots use it to learn how to fly. It is also the basis of modern instrumentation systems and a host of games, from cheap children's toys to the virtual reality devices which are now appearing in entertainment parks.

The software implementing interactive graphics systems can best be described using three levels of abstraction, namely the functional, procedural and device levels.
Data Flow Analysis and Design
Authors: Stevens Wayne P.
Published: February 2015

Data flow is the name applied when data are passed from one thing to another. The “thing” that passes the data can include a piece of software or an application, a computer or a region in a computer, a person, group, or organizational unit, or combinations of these. The data passed can be simple or complex and it can be passed as a stream or a unit. A diagram that depicts objects or processes and the possible flows of data among them is called a data flow diagram (DFD). DFDs are useful for depicting information about how an organization operates; the interfaces between an application and the people or other applications that use it; and the high‐level design of an application. DFDs have been used in application development for a long time.

There are two alternatives to (pure) data flow and each alternative has substantial disadvantages when used to link software components. One of these alternatives to data flow is for the data
not
to flow; that is, have various software modules access it directly in shared common data areas. A second alternative to pure data flow is the “call” statement, used in most languages to link subroutines. The call statement has two substantial limitations versus pure data flow: it also passes control and it explicitly names the target subroutine.

In today's application development methodologies, DFDs are important for: analyzing organizational units; depicting the context of an application relative to users and other applications; designing the high level (process) architecture of applications; showing the interfaces between application processes and data stores; and documenting batch job streams. DFDs are likely to be increasingly important for designing distributed systems, object‐oriented design, depicting asynchronous components, and for reusable code. An examination of each is given.
Data Modeling
Authors: Appleton Daniel S.
Published: February 2015

Any organization, whether a business, a government agency, a religion, a family, or any functional human unit, is a jungle of transactions, and these transactions are 99% logical. The vast majority of these transactions are
messages
sent from senders to receivers. The relationship between these two roles is crucial. A sender does not really know if a message it sends has any value to a receiver. From the standpoint of a receiver, each message it receives falls into one of two categories. If the message resolves some uncertainty in the receiver, or, if it adds to the receiver's knowledge or stimulates action, it is an
information message.
If it does none of these things, it is a
noise message
. Information messages, are positive forces in an organization, whereas noise messages are negative forces. The ratio of information messages received to all messages sent is the measure of the information quality of an organization. As this ratio approaches 1, the efficiency and effectiveness of the organization become optimum. This logic commutes the idea of
information
from a passive concept in organizational theory, to an active force for organizational growth and survival.

It is entirely presumptuous to assume that a sender can know for sure whether a message it sends will be an information message or a noise message to a receiver. At best, the sender can only work to increase the
probability
that its messages will be information messages and not noise messages. And this is where management must focus its attention. A primary aspiration of organizational management must be to increase information quality in the organization by concentrating on increasing the probability that messages sent from its senders to its receivers will be information messages and not noise messages. The question then becomes: “How do we increase the probability of information messages?” The answer, as we shall see, lies in an information engineering technology called Data Modeling.

This article covers three aspects of data modeling. First it will cover why we data‐model. Then it will present a sample data modeling technique, and examine how data models are built. Finally, it will discuss nine different applications of data modeling.
Domain Engineering
Authors: Czarnecki Krzysztof
Published: February 2015

Domain engineering(DE) is the systematic process of collecting, organizing, and storing past experience in building systems in a particular domain. This experience is captured in the form of reusable assets (i.e., reusable work products), such as documents, patterns, reusable models, components, generators, and domain‐specific languages. An additional goal of DE is to provide an infrastructure for reusing these assets (e.g., retrieval, qualification, dissemination, adaptation, and assembly) during application engineering, i.e., the process of building new systems.

By definition, DE focuses on system families rather than single systems. This focus sets it apart from the more traditional software development models, which are geared toward developing one‐of‐a‐kind systems. As a result, DE is the approach of choice for developing product lines and system families, component libraries, frameworks, domain‐specific languages, and generators.

Similar to the traditional single‐system software engineering, DE also encompasses the three main process components of analysis, design, and implementation. In this context, however, they are referred to asdomain analysis,domain design, anddomain implementation. The qualifier “domain” emphasizes the multisystem scope of these activities. This article describes each of them. An example is given.
Extreme Programming (XP)
Authors: Tracz Will
Published: February 2015

eXtreme Programming (XP) is a lightweight software development methodology based on the widely recognized and effective paradigms of code inspections, iterative spiral development, integrated product development teams (i.e., full‐time customer involvement), frequent builds, programmer teams (i.e., pair programming), design patterns, refactoring, coding standards, risk analysis, and regression testing. XP emerged from the object‐oriented programming community.

XP is “extreme” in the sense that it diverges from “traditional” software development methodologies in several ways. In particular, it discourages documentation and encourages a willingness to throw code away.

The XP approach to software development is targeted at systems with vague and changing requirements, a short delivery schedule, and limited resources.

XP is based on four “values” that are assumed to be embraced by those participating in the software development process:Communication;Simplicity;Feedback; andCourage.
Hypertext for Software Engineering
Authors: Scacchi Walt
Published: February 2015

What is the power of hypertext in supporting software engineering? (The term “hypertext” is treated throughout as synonymous with “hypermedia,” which denotes the nonlinear representation of interrelated textual, graphic, filmic, or auditory information.) Power in other contexts usually refers to the ability of some entity or agent to affect the behavior of another or to achieve advantage over another in ways that the other cannot avoid. Following this, one might expect that as atechnology, hypertext systems offer relative advantage over alternatives to automated text/document information systems, including conventional word processing systems, file systems, and database management systems.

Hypertext systems offer a degree of information processing power that enables new kinds of applications, much like the advent of expert system shells enabled the creation of expert applications for domains such as computer configuration and diagnostic pathology. Similarly, as amediumfor writing and reading electronic documents hypertext systems allow the redefinition of the structure and content of documents that alter the constraints and opportunities for conveying information in contrast to the linear print medium. Thus the power of hypertext in whatever form it exists is subtle and incremental; it is potential rather than kinetic. However, such power can accumulate in different application domains in the long run if effectively mobilized and integrated with domain‐specific tasks, processing mechanisms, and workflows.

The power of hypertext technology in different application domains can be realized in a number of ways. In particular, technology that supports a unified view of the hypertext documents, production processes, processing mechanisms, and settings of use appears to offer the greatest power at this time. To see this, the concept of a domain‐specific hypertext environment (DSHE) is defined in the following section. Next, the domain of software production is examined in order to identify how hypertext tools and document production/consumption techniques can play a role to facilitate software engineering objectives. The focus then shifts to describe the structure of information to evolve within a DSHE in terms of product, task, and setting information for the domain of software production. Together, these sections then set the final stage for a discussion of the power of DSHE. Subsequently, seven ways the power of DSHE can be realized are identified, followed by an examination of the costs that are borne in order to realize this power.
Information Age
Authors: Eisner Howard
Published: February 2015

The Information Age is a period of time, or era, in which information itself, in its various forms, constitutes a key or dominant ingredient in our delivery of products and services. The Information Age began to emerge in a most serious manner about halfway through the twentieth century, when, for the first time, white collar workers started to outnumber blue collar employees.

Advances such as successes in telegraphy, telephony, radio, television, xerography, larg scale computers, etc; provided initial fuel for the Information Age engine by proving the importance of information‐related technologies and demonstrating their economic value in the marketplace. Two additional and extremely significant sets of events included the refinement and market penetration of the personal computer (PC), along with its resident applications, and connectivity to the Internet. These events were acknowledged, in the aggregate, as “trends that were shaping the 1980s” in shifting from an industrial society to an information society. In doing so, at least four key points were considered to be critical:

The reality and influence of the information‐oriented society

Computers and communications coming together to support each other

New information technologies migrating from old industrial activities to new processes

The need for our education system to step up to difficult challenges associated with the new information orientation

These key points are discussed in this article.
Jackson Development Methods
Authors: Jackson Michael
Published: February 2015

The Jackson Development Methods are JSP (Jackson Structured Programming) and JSD (Jackson System Development). JSP is a method for designing programs as compositions of sequential processes; JSD is a method for specifying and designing systems whose application domain has a strong temporal flavor and contains objects whose behavior is describable in terms of sequences of events. Many program and system development problems thus fall within the scope of JSP and JSD and these methods have been used to develop data processing systems, control systems, systems software, embedded systems, and even a music synthesizer.

JSP and JSD differ from some widely used methods in two main respects. First, unlike other methods, they pay attention initially to the domain of the software and only later to the software itself. Their first describe not the software, but its subject matter. Second, they focus on time‐ordering: on event sequencing rather than on static data models. For a JSP program, the domain is the time‐ordered streams of records or of events that the program must process. For a JSD system, the domain is the real world in which the entities exhibit concurrent time‐ordered behaviors that the system must model and compute about. If JSD entities are regarded as objects, JSD may be said to be object‐oriented.

The basic idea is to describe the structures of the sequential streams as regular languages and to form the structure of the program by composing the stream languages into one superset regular language.

Program inversion technique is an important element in the progression from JSP to JSD. Two other important elements are the recognition and resolution of interleaving clashes and an implementation technique—state‐vector separation—used to deal with the resulting multiplicity of processes.

The development steps of JSD as originally formulated are six: the entity action step; the entity structure step; the initial model step; the function step; the system timing step; and the implementation step.

These steps were later modified and rearranged into three development phases: the modeling phase; the network phase; and The implementation phase.

Explanation here follows the broad lines of this later formulation and also draws on some later refinements and elaborations of the method.
Knowledge Bases
Authors: Pease Adam , Liuzzi Raymond A. , Gunning David
Published: February 2015

In this article we present an overview of knowledge‐based systems. We begin by discussing the basic characteristics of knowledge base rules and present an example comparing a toy knowledge base to an equivalent procedural version of the same code. We then discuss the applications for which it makes sense to use knowledge‐based technology and the advantages offered by reuse of a general‐purposeupper ontology. Next we describe important research and applications in both knowledge representation and knowledge‐based systems. We then describe how work in philosophy and other research has had an impact on knowledge‐based systems. We conclude with thoughts on where the field is heading.
Linux
Authors: Bollinger Terry
Published: February 2015

Linux
(pronounced LIN‐ucks) is the common name for any well‐defined collection of system and application software (a
distribution
) that uses the UNIX‐like
Linux kernel
for its basic operating system services, such as process control, memory allocation, device management, file access, and networking. To qualify as a Linux distribution, such a collection of software must also consist entirely or almost entirely of freely redistributable, public‐source software, which is variously known as
free
,
open
, or sometimes
libre
software. Linux is most commonly used on Intel x86/Pentium‐based personal computers (PCs), but it has also been ported to a large and growing non‐x86 computers of diverse ages, sizes, and capabilities. Linux is notable for having achieved a level of public awareness and stockmarket notice second only to Microsoft Windows.

This article discusses the history of Linux, the design of the Linux kernel, Linux development, the role of Linux distributions, and possible future directions of this intriguing operating system.
Model‐Based Software Testing
Authors: El‐Far Ibrahim K. , Whittaker James A.
Published: February 2015

There is an abundance of testing styles in the discipline of software engineering today. Over the last few decades, many of these have come to be used and adopted by the industry as solutions to address the increasing demand for assuring software quality. Since 1990 or so, perhaps as an outcome of the popularization of object orientation and models in software engineering, there has been a growth in black‐box testing techniques that are collectively dubbedmodel‐based testing. Model‐based testing (MBT) is a general term that signifies an approach that bases common testing tasks such as test case generation and test result evaluation [see Jorgensen (1995) for some of these basic terms and concepts] on a model of the application under test.

This generic definition is probably the least general statement that can be made about MBT. One of the striking issues about MBT is the nonstandard lingo that reflects a diversity of philosophies and models. Another issue that one will eventually realize in studying this set of techniques is that the models and techniques have yet to travel the long course to maturity. Disregarding these concerns, model‐based techniques have gained the attention of practitioners and theoreticians alike. The wealth of published work portraying case studies in both academic and industrial settings is a sign of the newfound interest in this youthful branch of testing.

Model‐based techniques have substantial appeal. The first sign of potential are studies showing that testing a variety of applications has been met with success when MBT was employed. This article discussed what a model is and gives some models that have been useful for testing. Information given or choosing a module, building it, and testing it, The present and future status of model‐based software testing is detailed.