Web-based education experiences

The World Wide Web has the potential to revolutionize instruction and increase educational opportunities across corporate, government and educational sectors. Not only will the Web enable distance learning and peer-to-peer connectivity, but it will also enhance student feedback and let instructors understand whether and how long students have studied a particular lesson. It also has the potential to reduce training costs. The authors discuss the creation of an online learning environment considering practical and pedagogical issues     

A practitioner's guide to data base compression tutorial

Data compression techniques can improve information system performance by reducing the size of a database by as much as ninety percent. This paper is written to provide assistance to practitioners considering the use of data compression for the storage of a commercial database. It reviews a wealth of literature on data compression and presents facts and guidelines which will assist system designers in evaluating the costs and benefits of compression and in selecting techniques appropriate for their needs.     

Sex chromosome meiotic drive in stalk-eyed flies

Meiotically driven sex chromosomes can quickly spread to fixation and cause population extinction unless balanced by selection or suppressed by genetic modifiers. We report results of genetic analyses that demonstrate that extreme female-biased sex ratios in two sister species of stalk-eyed flies, Cyrtodiopsis dalmanni and C. whitei, are due to a meiotic drive element on the X chromosome (Xd). Relatively high frequencies of Xd in C. dalmanni and C. whitei (13-17% and 29%, respectively) cause female-biased sex ratios in natural populations of both species. Sex ratio distortion is associated with spermatid degeneration in male carriers of Xd. Variation in sex ratios is caused by Y-linked and autosomal factors that decrease the intensity of meiotic drive. Y-linked polymorphism for resistance to drive exists in C. dalmanni in which a resistant Y chromosome reduces the intensity and reverses the direction of meiotic drive. When paired with Xd, modifying Y chromosomes (Ym) cause the transmission of predominantly Y-bearing sperm, and on average, production of 63% male progeny. The absence of sex ratio distortion in closely related monomorphic outgroup species suggests that this meiotic drive system may predate the origin of C. whitei and C. dalmanni. We discuss factors likely to be involved in the persistence of these sex-linked polymorphisms and consider the impact of Xd on the operational sex ratio and the intensity of sexual selection in these extremely sexually dimorphic flies.     

Physicochemical and toxicological properties of commercial carbon blacks modified by reaction with ozone

Ozonation of two commercial carbon blacks (CBs), Printex 90 (P90) and Flammruss 101 (F101), was carried out and changes in their morphology, physical properties, and cytotoxicity were examined. The hypothesis examined was that different methods of manufacture of CBs influence their chemical reactivity and toxicological properties. Structural changes were examined by X-ray photoelectron spectroscopy, infrared spectroscopy, Raman spectroscopy, and electron paramagnetic resonance spectroscopy (EPR). Introduction of surface oxygen functionality upon ozonation led to changes in surface charge, aggregation characteristics, and free radical content of the CBs. However, these changes in surface functionality did not alter the cytotoxicity and release of inflammation markers upon exposure of the CBs to murine macrophages. Interaction of macrophages with F101 resulted in higher levels of inflammatory markers than P90, and the only structural correlation was with the higher persistent radical concentration on the F101.     

The value of the formal standards process

The purpose of this article is to critique the process of developing formal standards, which are those that have been approved by an official standards-making body. The bodies that impact US computer standards most include the International Standards Organization (ISO), the International Telecommunications Union (ITU), the American National Standards Institute (ANSI) and the Institute of Electrical and Electronics Engineers (IEEE). Other groups develop important standards that are outside the formal process. These include the Open Software Foundation (OSF), X/Open, and the Internet Engineering Task Force (IETF). The main difference between a formal standards organization and the other groups is the legal framework in which the body operates. The formal organizations are often chartered by the government with strict procedures and rules imposed on the standards development process. OSF and X/Open are each directed by a board of directors, whereas the IETF is an independent, self-governing body that develops its own rules and procedures     

Linking computers and consumer electronics

The capabilities of our personal computers have increased dramatically over the past 15 years, and so has the number of connectors on the back of our systems. Originally, we needed a serial port for a modem and a parallel port for a printer. Now we also need ports for a mouse, audio input, audio output, video input, video output, Ethernet, and a camera. Enter the IEEE 1394 standard known as Firewire. This standard proposes to provide a single port on the back of our computers that can handle nearly all of the communication for which we now need eight to 10 ports. Along with connecting standard peripherals to computers, Firewire is designed for use with consumer audio, video, and television equipment     

What is a profile? [computer standards]

Discusses the value of profiles and how they differ from standards. Profiles address the problem of computer standards not being precisely designed to meet end-user needs. A standard's scope is generally much narrower than an entire computer system. To support user needs, a particular computer system may have to comply with many individual standards. Several factors may limit the scope of each standard. Moreover, no formal standards body requires that standards completely address end-user needs. Finally, a standard's scope is often reduced because an area originally covered by the standard does not have sufficient consensus to be retained in that standard. A consensus-based standard can be produced only in those areas that have sufficient consensus. Profiles are specifications that formally capture an organization's information technology needs. They are becoming a way to map the middle ground between overall user needs and the standards related to those needs. Profiles can be used to inventory an existing computing strategy, support a computing procurement or drive the evolution of an organization's computing strategy. Actually, organizations have been developing profiles for many years. However, they've gone by such names as procurement specifications, bid documents, strategic plans or recommended practices. At a minimum, a profile identifies user requirements and the standards or specifications that meet those requirements. A profile may also include more details on an organization's computing strategy