Wind energy systems

Wind energy has matured to a level of development where it is ready to become a generally accepted utility generation technology. A brief discussion of this development is presented, and the operating and design principles are discussed. Alternative designs for wind turbines and the tradeoffs that must be considered are briefly compared. Development of a wind energy system and the impacts on the utility network including frequency stability, voltage stability, and power quality are discussed. The assessment of wind power station economics and the key economic factors that determine the economic viability of a wind power plant are presented     

The NC-REN meets the North Carolina Information Highway

The North Carolina Research and Education Network (NC-REN), formerly known as CONCERT, is an existing video and data network, owned and operated by MCNC. NC-REN's purpose has been to provide network-based support for collaboration in the research community within the state since 1985. The first major application planned for the North Carolina Information Highway (NCIH) is an interactive video distance learning system. A secondary application proposed is the use of Switched Multimegabit Data Service (SMDS) as a means of providing data communications services over NCIH. The user community currently supported by NC-REN has come to expect high levels of service, reliability, interoperability and performance for data and video communications. MCNC is committed to see that NC-REN users receive service that is equal to or better than what is currently provided by the existing network. The prospect of migrating NC-REN-provided services to NCIH-provided transport has raised challenging technical and unique service issues     

Clonidine therapy for comorbid attention deficit hyperactivity disorder and conduct disorder: preliminary findings in a children's inpatient unit

This retrospective study examined the clinical course of 18 prepubertal boys (aged 6 to 12) who had dual diagnoses of attention deficit hyperactivity disorder and conduct disorder and who received clonidine on an inpatient basis after failed trials of conventional drug therapy, consisting predominantly of psychostimulants. The effects of clonidine were assessed during inpatient treatment and after discharge at intervals of 1 to 2 months. Eleven (61%) of the children had marked improvement as measured by clinical impression. Transient sedation lasting 2 to 3 days occurred after initial administration or dosage increase; otherwise, clonidine was well tolerated. Our findings suggest that clonidine may prove to be an alternative treatment of comorbid attention deficit hyperactivity disorder and conduct disorder.     

Protein-lipid interactions in concentrated infant formula

Radiolabeled milk proteins ([carbon-14] beta-lactoglobulin or [carbon-14] kappa-casein) were added to raw skim milk used to prepare concentrated humanized infant formula. Ultracentrifugation of the sterilized product allowed separation of three fractions: lipids and the proteins associated with them; free casein micelles and other dense particles; and the fluid phase. Distribution of radiolabeled tracer proteins or of protein measured by chemical methods among these three phases varied significantly with differences in processing conditions (time and temperature of sterilization) or amount of certain additives (potassium hydroxide or urea). In the range of 0 to 8 meq/L of potassium hydroxide added to the formula after homogenization but before sterilization, the lipid layer content of carbon-14 from [carbon-14] kappa-casein in the sterilized product decreased by 4.7% for each 1 meq/L of added potassium hydroxide. Lipid layer content of protein decreased by 2 g/L (of a total of 32 g/L) for each 1 meq/L potassium hydroxide. Such differences in the structure of the product, related to interactions of protein with lipid, protein, or calcium phosphate, may correlate with physical properties and stability of milk-based lipid-rich products.     

The layman's view of orthodontics: a literary review

It is probably true to say that the masticatory apparatus attracts proportionally greater attention than any other part of the body. Evidence that this is so is provided, not only by the degree of specialisation within the dental profession, but by the frequency with which references to teeth and dentistry crop up in literature. Generations of biographers, novelists, poets, playwrights and essayists have written about their dental experiences and included the dentition in describing the facial appearance of characters, factual and fictional. The literary extracts in this article, culled from an extensive collection, refer to orthodontics. They provide a fascinating insight into the patient's perspective on that speciality and make entertaining reading.     

Kinetics of Slag Hydration in the Presence of Calcium Hydroxide

The reaction between ground granulated blast furnace slag (GGBFS) having an empirical formula of C_7.88S_7.39M₃A and calcium hydroxide (CH) was investigated. The kinetics of the reaction were explored. Thermogravimetric analysis was used to monitor the consumption of CH from which rate constants were determined. Based on Knudsen's kinetic model, activation energies of 14.5, 17.9, and 22.6 kJ/mol were determined for three different mass ratios of slag and CH reacted over a temperature range of 15° to 50°C and hydrated for a period of time from 0 to 32 days. A comparison of the kinetics of the slag/CH reaction was made with slag/portland cement hydration. The basic features of both appear similar.