Advancements in the Field of Direct Steam Generation in Linear Solar Concentrators—A Review

Direct steam generation in parabolic trough or linear Fresnel collectors represents one interesting technological option for concentrating solar electricity production. Today's state of the art characterized by the first commercial plants in operation is a result of more than 20 years of intensive research on this topic. This article provides a review on the key results from research that includes physical effects like heat transfer and pressure drop in horizontal boiler tubes, plant layout considerations, and thermal storage options. An overview on test and demonstration facilities as well as on commercial plants is given, leading to an outlook on the next generation of direct steam generation systems.     

Information technology in Nigerian banks: The limits of expectations

In the last ten years, banks in developed countries have been investing more and more in information technology (IT) as a means to reduce costs and improve operational efficiency. An investigation of the application of IT in Nigerian banks was carried out in order to determine the expectations and success of IT implementations in the sector. The data were generated from a survey of randomly selected branches of 56 banks in Lagos, the commercial capital of Nigeria. Almost all the banks had an IT policy, the main thrusts of which where to achieve full application of IT, to be able to meet organisational goals, to secure competitive advantage, and to be up to date. Only 54.6% of them actually achieved some measure of successful implementations. The expected benefits of investment in IT were realised in only a relatively few number of banks. The consequence was that less than 40% of the banks were poised to maximise the benefits of IT through major investments, especially in the areas of online access and transactions, electronic commerce, and electronic publishing. It is estimated that at least 60% of the branches of these banks are spending less than $150,000 annually on IT. An upsurge of investment is, however, expected, first by the banks that style themselves as progressive and have already made some success in IT implementations, and later by the other banks.     

Novel low-voltage low-power high-precision CCII± based on bulk-driven folded cascode OTA

This paper presents possible approaches to the design of a novel low-voltage, low-power, and high-precision current conveyor of the second generation (CCII±) based on the bulk-driven folded cascode operational transconductance amplifier (OTA) with extended input common-mode voltage range. This CCII± utilizes bulk-driven differential pairs to obtain a nearly rail-to-rail input stage at a low supply voltage. The proposed conveyor operates at a low supply voltage of ±400 mV with a reduced power consumption of only 64 μW. A current-mode multifunction filter is presented as an application of the CCII±. This filter provides five transfer functions simultaneously, namely low-pass, band-pass, high-pass, notch, and all-pass. The filter has the following properties and advantages: it employs three bulk-driven current conveyors BD-CCII±, three grounded resistors, and two grounded capacitors, which is suitable for integrated circuit implementation. Furthermore, the input signal is connected to the low-impedance X terminal of the BD-CCII± whereas the output signals are taken from the high-impedance output terminals Z+ and Z−. Finally, the pole frequency and quality factor of the designed filter are tunable independent of each other. PSpice simulation results using the 0.18 μm CMOS technology are included to prove the results.     

Making Epothilones Fluoresce: Design,Synthesis, and Biological Characterization of a Fluorescent N12‐Aza‐Epothilone (Azathilone)

A green fluorescent 12‐aza‐epothilone (azathilone) derivative has been prepared through the attachment of the 4‐nitro‐2,1,3‐benzoxadiazole (NBD) fluorophore to the 12‐nitrogen atom of the azamacrolide core structure. While less potent than natural epothilones or different N12‐acylated azathilone derivatives, NBD‐azathilone ( 3 ) promotes tubulin assembly, inhibits cancer cell proliferation in vitro and arrests the cell cycle at the G2/M transition. Most significantly, the binding of 3 to cellular microtubules (MTs) could be directly visualized by confocal fluorescence microscopy. Based on competition binding experiments with laulimalide‐stabilized MTs in vitro, the N12‐Boc substituted azathilone 1 , Epo A, and NBD‐azathilone ( 3 ) all interact with the same tubulin‐binding site. Computational studies provided a structural model of the complexes between β‐tubulin and 1 or 3 , respectively, in which the NBD moiety of 3 or the BOC moiety of 1 directly and specifically contribute to MT binding. Collectively, these data demonstrate that the cellular effects of 3 and, by inference, also of other azathilones are the result of their interactions with the cellular MT network.     

Third-order optical nonlinear studies of Cobalt (II) Schiff base complex bearing triphenylphosphine using Differential Optical Kerr Gate and Z-scan studies

The third-order optical nonlinearity of the composite film of coordination complex [CoLPPh₃Cl] (L = N-(2-pyridyl)-N′-(salicylidene)hydrazine) and PMMA has been investigated by using Differential Optical Kerr Gate (DOKG) and Z-scan measurements. Large value of the third-order nonlinear optical susceptibility (χ⁽³⁾) of the order of 10^?10 esu was measured and its nonlinear response time was found to be faster than or comparable to the laser pulse width (90 fs) used. The single beam Z-scan technique was used to investigate the nonlinear absorption property of the composite near 800 nm. The sample exhibit saturable absorption. The nonlinear absorption coefficient of sample is found to be ?32 cm/GW.     

Prognostic value of blood lactate, base deficit, and oxygen-derived variables in an LD50 model of penetrating trauma

OBJECTIVE: To determine whether blood lactate, base deficit, or oxygen-derived hemodynamic variables correlate with morbidity and mortality rates in a clinically-relevant LD50 model of penetrating trauma. DESIGN: Prospective, controlled study. SETTING: University research laboratory. SUBJECTS: Anesthetized, mechanically-ventilated mongrel pigs (30+/-2 kg, n = 29). INTERVENTIONS: A captive bolt gun delivered a penetrating injury to the thigh, followed immediately by a 40% to 60% hemorrhage. After 1 hr, shed blood and supplemental crystalloid were administered for resuscitation. MEASUREMENTS AND MAIN RESULTS: After penetrating injury, 50.7+/-0.3% hemorrhage (range 50% to 52.5%), and a 1-hr shock period, seven of 14 animals died, compared with six of six animals after 55% to 60% hemorrhage, and 0 of nine animals after < or =47.5% hemorrhage. Only two of 13 deaths occurred during fluid resuscitation. At the LD50 hemorrhage, peak lactate concentration and base deficit were 11.2+/-0.8 mM and 9.3+/-1.5 mmol/L, respectively, and minimum mixed venous oxygen saturation, systemic oxygen delivery, and systemic oxygen consumption were 33+/-5%, 380+/-83 mL/min/kg, and 177+/-35 mL/min/kg, respectively. For comparison, baseline preinjury values were 1.6+/-0.1 mM, -6.7+/-0.6 mmol/L, 71+/-3%, 2189+/-198 mL/min/kg, and 628+/-102 mL/min/kg, respectively. Of all the variables, only lactate was significantly related to blood loss before and after fluid resuscitation in the 16 survivors. However, r2 values were relatively low (.20 to .50), which indicates that only a small fraction of the hyperiactacidemia was directly related to tissue hypoperfusion. In the whole population of survivors and nonsurvivors, both lactate and base deficit (but none of the oxygen-derived variables) correlated with blood loss. CONCLUSIONS: Arterial lactate is a stronger index of blood loss after penetrating trauma than base deficit or oxygen-derived hemodynamic variables. The reliability of arterial lactate depends on several factors, such as the time after injury, the proportion of survivors and nonsurvivors in the study population, and on factors other than tissue hypoxia.     

Referenzmodellierung für E-Government-Services

The realisation of E-Government Services in Switzerland makes only little progresS. Reasons are — on the one hand — the federal constitution of the Swiss Confederation. On the other hand, public administrations are concerned about the high initial effort and the corresponding financial investmentS. As a partner in the EU–funded project OntoGov the Swiss Federal Chancellery now takes over an active role in the configuration of E–Government services. With the OntoGov system reference process models are provided at various abstraction layerS. Public administrations can adapt these reference models to their specific needs and make them available for the citizenS. Decisions for designing and adapting reference processes are explicitly modelled using ontologies, making the decision process traceable. Thus, subsequent changes in the reference models can be transferred to all the depending models.     

Noniatrogenic esophageal trauma

Few guidelines are available with which to facilitate treatment in patients with noniatrogenic injuries of the esophagus. Early diagnosis and proper management are essential if a good outcome is to be expected. In an effort to define better the treatment of patients with penetrating and blunt injuries of the esophagus, we report our recent 5-year experience at an urban trauma center. From July 1988 to June 1993, nineteen patients with esophageal perforations from penetrating (18) and blunt (1) trauma were identified by our trauma registry. There was no mortality in this group of patients and morbidity was mostly due to associated injuries. Eleven cervical esophageal injuries were repaired. One cervical injury was treated by stopping oral intake and giving intravenous antibiotics. The neck was not drained in 10 of the surgical cases. In 1 patient a tracheoesophageal fistula developed, which later was repaired with a pectoralis muscle flap. Seven perforations were identified in the thoracic (2) and abdominal (5) portions of the esophagus. All were due to gunshot wounds. In 4 cases, a fundal wrap was used to reinforce the repairs. Postoperative contrast studies confirmed that all repairs were intact. We conclude that penetrating and blunt tears of the esophagus can be repaired safely with minimal mortality. Morbidity is usually from associated injuries such as to the spinal cord and trachea. When identified early, cervical esophageal injuries do not need to be drained routinely.     

Safety Evaluation for Campus Parking Garage Performance Using Fuzzy Logic

Crime has been plaguing parking garages in the United States. At The Ohio State University, (OSU) crime on campus, in general, has decreased in recent years; however, crime in OSU parking garages has remained stable in spite of campus-wide efforts to reduce crime. When assessing and evaluating parking garages, occupants employ experience-based judgment that is subjective and imprecise, yet extremely useful. When designers employ the principles of crime prevention through environmental design, they also use subjective variables. An approach that captures the imprecise information in noncrisp expressions reflecting subjective and experience-based variables is the fuzzy logic concept. This concept allows the use of mathematical operations to manipulate and operate on imprecise information or knowledge. Variables such as garage illumination and wall height were collected, fuzzified, and treated as the knowledge base of a model presented in this paper. In addition, numerous experience-based implication rules were developed and employed to evaluate subjective variables. A computer program was developed to illustrate implementation of the model.