High frequency, high power capacitor development

A program to develop a special high energy density, high power transfer capacitor to operate at frequency of 40 kHz, 600 V rms at 125 A rms plus 600 V dc bias for space operation. The program included material evaluation and selection, a capacitor design was prepared, a thermal analysis performed on the design. Fifty capacitors were manufactured for testing at 10 kHz and 40 kHz for 50 hours at Industrial Electric Heating Co. of Columbus, Ohio. The vacuum endurance test used on environmental chamber and temperature plate furnished by Maxwell. The capacitors were energized with a special power conditioning apparatus developed by Industrial Electric Heating Co. Temperature conditions of the capacitors were monitored by IEHCo test equipment. Successful completion of the vacuum endurance test series confirmed achievement of the main goal of producing a capacitor or reliable operation at high frequency in an environment normally not hospitable to electrical and electronic components. The capacitor developed compared to a typical commercial capacitor at the 40 kHz level represents a decrease in size and weight by a factor of seven

Spectral weight redistribution in (LaNiO3)n/(LaMnO3)2 superlattices from optical spectroscopy

We have studied the optical properties of four (LaNiO$_3$)$_n$/(LaMnO$_3$)$_2$ superlattices (SL) ($n$=2, 3, 4, 5) on SrTiO$_3$ substrates. We have measured the reflectivity at temperatures from 20 K to 400 K, and extracted the optical conductivity through a fitting procedure based on a Kramers-Kronig consistent Lorentz-Drude model. With increasing LaNiO$_3$ thickness, the SLs undergo an insulator-to-metal transition (IMT) that is accompanied by the transfer of spectral weight from high to low frequency. The presence of a broad mid-infrared band, however, shows that the optical conductivity of the (LaNiO$_3$)$_n$/(LaMnO$_3$)$_2$ SLs is not a linear combination of the LaMnO$_3$ and LaNiO$_3$ conductivities. Our observations suggest that interfacial charge transfer leads to an IMT due to a change in valence at the Mn and Ni sites.Comment: Accepted for publication in Phys. Rev. Lett. 5 pages, 5 figure

Certificate Of Online Learning And Teaching (COLT) At The University Of Hawaii: A Horse Of Another Color For Earning College Credits

Current conventional wisdom may perceive that higher education is outdated and maybe even likely to collapse. Online education is often predicted to replace brick-and-mortar campuses with systems providing students access to world-class learning via smartphones and tablets. Many private and commercial ventures are embracing such concepts. However, in the race to implement large-scale models, significant key elements such as understanding that learning can be social, affective, personal, and even cultural may be missing. Thus, creative yet research-based programs at the university level are needed. While it is true that existing university structures might inhibit the implementation of radical programs, there are opportunities where such innovation can be offered. In the case of the Department of Educational Technology at the University of Hawaii, an option for a program at the certificate level not necessarily leading to a traditional degree was provided. The certificate option provided an opportunity to explore entrepreneurial models while also incorporating what we understand about learning, the brain, and newer technologies. This paper describes the circumstances and approach that led to the creation of an innovative program that still fit within current university structures

Ultrahigh Transmission Optical Nanofibers

We present a procedure for reproducibly fabricating ultrahigh transmission optical nanofibers (530 nm diameter and 84 mm stretch) with single-mode transmissions of 99.95 $\pm$ 0.02%, which represents a loss from tapering of 2.6 $\,\times \,$ 10$^{-5}$ dB/mm when normalized to the entire stretch. When controllably launching the next family of higher-order modes on a fiber with 195 mm stretch, we achieve a transmission of 97.8 $\pm$ 2.8%, which has a loss from tapering of 5.0 $\,\times \,$ 10$^{-4}$ dB/mm when normalized to the entire stretch. Our pulling and transfer procedures allow us to fabricate optical nanofibers that transmit more than 400 mW in high vacuum conditions. These results, published as parameters in our previous work, present an improvement of two orders of magnitude less loss for the fundamental mode and an increase in transmission of more than 300% for higher-order modes, when following the protocols detailed in this paper. We extract from the transmission during the pull, the only reported spectrogram of a fundamental mode launch that does not include excitation to asymmetric modes; in stark contrast to a pull in which our cleaning protocol is not followed. These results depend critically on the pre-pull cleanliness and when properly following our pulling protocols are in excellent agreement with simulations.Comment: 32 pages, 10 figures, accepted to AIP Advance

Planning For Evaluation In Online Learning: University Of Hawaii Case Study

With contemporary requirements for objective measurement, program evaluation is a certain necessity. Most program evaluation is designed in response to external demands for assessment. Moreover, such evaluation is typically developed only after programs already exist. However, the proliferation of online learning provides new opportunities for approaching evaluation. Specifically, many higher education institutions are currently augmenting existing campus-based programs with online learning—either by hybridizing traditional delivery or by providing parallel online options. At the University of Hawaii, while designing a parallel online delivery model for an existing campus-based program, careful consideration was given to the unique requirements for evaluation and assessment. In this way, an overall plan for evaluation was developed that incorporated multiple layers of assessment: from specific programmatic to internal university to external accreditation requirements. Commonalities among the multiple layers were considered to develop a single, overall evaluation approach. In a case study model, this paper describes eight practical steps taken to develop an overall, effective evaluation model

Near Infrared Spectroscopic Monitoring During Cardiopulmonary Exercise Testing Detects Anaerobic Threshold

Cardiopulmonary exercise testing (CPET) provides assessment of the integrative responses involving the pulmonary, cardiovascular, and skeletal muscle systems. Application of exercise testing remains limited to children who are able to understand and cooperate with the exercise protocol. Near-infrared spectroscopy (NIRS) provides a noninvasive, continuous method to monitor regional tissue oxygenation (rSO2). Our specific aim was to predict anaerobic threshold (AT) during CPET noninvasively using two-site NIRS monitoring. Achievement of a practical noninvasive technology for estimating AT will increase the compatibility of CPET. Patients without structural or acquired heart disease were eligible for inclusion if they were ordered to undergo CPET by a cardiologist. Data from 51 subjects was analyzed. The ventilatory anaerobic threshold (VAT) was computed on VCO2 and respiratory quotient post hoc using the standard V-slope method. The inflection points of the regional rSO2 time-series were identified as the noninvasive regional NIRS AT for each of the two monitored regions (cerebral and kidney). AT calculation made using an average of kidney and brain NIRS matched the calculation made by VAT for the same patient. Two-site NIRS monitoring of visceral organs is a predictor of AT

Surface-associated heat shock proteins of Legionella pneumophila and Helicobacter pylori: roles in pathogenesis and immunity.

Bacterial heat shock proteins (Hsps) are abundantly produced during the course of most microbial infections and are often targeted by the mammalian immune response. While Hsps have been well characterized for their roles in protein folding and secretion activities, little attention has been given to their participation in pathogenesis. In the case of Legionella pneumophila, an aquatic intracellular parasite of protozoa and cause of Legionnaires' disease, Hsp60 is uniquely located in the periplasm and on the bacterial surface. Surface-associated Hsp60 promotes attachment and invasion in a HeLa cell model and may alter an early step associated with the fusion of phagosomes with lysosomes. Avirulent strains of L. pneumophila containing defined mutations in several dot/icm genes are defective in localizing Hsp60 onto their surface and are reduced approximately 1000-fold in their invasiveness towards HeLa cells. For the ulcer-causing bacterium Helicobacter pylori, surface-associated Hsp60 and Hsp70 mediate attachment to gastric epithelial cells. The increased expression of these Hsps following acid shock correlates with both increased association with and inflammation of the gastric mucosa. A role for Hsps in colonization, mucosal infection and in promoting inflammation is discussed