Evolution of optical pulses in fiber lines with lumped nonlinear devices as a mapping problem

We analyze the steady-state propagation of optical pulses in fiber transmission systems with lumped nonlinear optical devices (NODs) placed periodically in the line. For the first time to our knowledge, a theoretical model is developed to describe the transmission regime with a quasilinear pulse evolution along the transmission line and the point action of NODs. We formulate the mapping problem for pulse propagation in a unit cell of the line and show that in the particular application to nonlinear optical loop mirrors, the steady-state pulse characteristics predicted by the theory accurately reproduce the results of direct numerical simulations. © 2005 Springer Science+Business Media, Inc.

Near-constant time delay response of fibre grating Sagnac loop filters

A theoretical and experimental investigation of the time delay characteristics of fiber Bragg grating-based Sagnac loops (FBGSLs) is presented. Analytic expressions for the phase and time delay of the FBGSL have been derived and excellent agreement is found between their predictions and experimental results for configurations incorporating uniform-period and chirped-period gratings. For symmetrical grating structures, it is found that the FBGSL time delay response is similar to that of the incorporated grating; with asymmetrical gratings, the FBGSL response is quite different. It is shown that wavelength-division-multiplexing filters exhibiting near-zero dispersion characteristics can be implemented using FBGSLs.

Using Reengineering Techniques for Distance Study Course Improvement

The paper analyses the reengineering concept as it comes from software engineering and management fields. We combine two viewpoints and apply them to solve a problem of reengineering of a distance study system, in general, and the unit of learning, in particular. We propose a framework for reengineering of unit of learning, based on general model of software reengineering, and present a case study, in which we describe, how one topic of distance study course was reengineered, considering triple consistency principle and requirements for computer science. The proposed framework contributes to increasing quality, effectiveness and systematization of delivering distance studies.

First Draft of Office for Student Affairs Structure

Chart illustrating the organizational structure of the College of Medicine's Student Affairs department.

Moving to the Front of the Classroom: English Graduate Students as Composition Instructors

This phenomenological study explores how graduate students in an English department perceive their new roles as writing teachers. The findings show that even though the participants went through the same professional development program, they constructed different teacher identities based on their other identities and their experiences as students and writers.

World-Class Service

In the discussion - World-Class Service - by W. Gerald Glover, Associate Professor, Restaurant, Hotel and Resort Management at Appalachian State University and Germaine W. Shames, Hilton International, New York, Glover and Shames initially state: “Providing world-class service to today's traveler may be the key for hospitality managers in the current competitive market. Although an ideal, this type of service provides a mandate for culturally aware managers. The authors provide insight into several areas of cultures in collision.” Up to the time this essay is written, the authors point to a less-than-ideal level of service as being the standard in the hospitality industry and experience. “Let's face it - if we're ever to resurrect service, it will not be by going back to anything,” Glover and Shames exclaim. “Whatever it was we did back then has contributed to the dilemma in which we find ourselves today, handicapped by a reactive service culture in an age that calls for adaptiveness and global strategies,” the authors fortify that thought. In amplifying the concept of world-class service Glover and Shames elaborate: “World-class service is an ideal. Proactive and adaptive, world-class service feels equally right to the North American dignitary occupying the Presidential Suite, and the Japanese tourist staying in a standard room in the same hotel.” To bracket that model the authors offer: “At a minimum, it is service perceived by each customer as appropriate and adequate. At its best, it may also make the customer feel at home, among friends, or pampered. Finally, it is service as if culture matters,” Glover and Shames expand and capture the rule of world-class service. Glover and Shames consider the link between cultures and service an imperative one. They say it is a principle lost on most hospitality managers. “Most [managers] have received service management education in the people are people school that teaches us to disregard cultural differences and assume that everyone we manage or serve is pretty much like ourselves,” say Glover and Shames. “Is it any wonder that we persist in setting service standards, marketing services, and managing service staff not only as if culture didn't matter, but as if it didn't exist?!” To offer legitimacy to their effort Glover and Shames present the case of the Sun and Sea Hotel, a 500-room first class hotel located on the outskirts of the capital city of a small Caribbean island nation. It is a bit difficult to tell whether this is a dramatization or a reality. It does, however, serve to illustrate their point in regard to management’s cognizance, or lack thereof, of culture when it comes to cordial service and guest satisfaction. Even more apropos is the tale of the Palace Hotel, “…one of the grande dames of hospitality constructed in the boom years of the 1920s in a mid-sized Midwestern city in the United States.” The authors relate what transpired during its takeover in mid-1980 by a U.S.-based international hotel corporation. The story makes for an interesting and informative case study.

The Beacon, January 11, 2007

Vol. 19, Issue 38, 8 pages

A Study of Stock Market Fluctuations and their Relations to Business Conditions

Most research on stock prices is based on the present value model or the more general consumption-based model. When applied to real economic data, both of them are found unable to account for both the stock price level and its volatility. Three essays here attempt to both build a more realistic model, and to check whether there is still room for bubbles in explaining fluctuations in stock prices. In the second chapter, several innovations are simultaneously incorporated into the traditional present value model in order to produce more accurate model-based fundamental prices. These innovations comprise replacing with broad dividends the more narrow traditional dividends that are more commonly used, a nonlinear artificial neural network (ANN) forecasting procedure for these broad dividends instead of the more common linear forecasting models for narrow traditional dividends, and a stochastic discount rate in place of the constant discount rate. Empirical results show that the model described above predicts fundamental prices better, compared with alternative models using linear forecasting process, narrow dividends, or a constant discount factor. Nonetheless, actual prices are still largely detached from fundamental prices. The bubble-like deviations are found to coincide with business cycles. The third chapter examines possible cointegration of stock prices with fundamentals and non-fundamentals. The output gap is introduced to form the non-fundamental part of stock prices. I use a trivariate Vector Autoregression (TVAR) model and a single equation model to run cointegration tests between these three variables. Neither of the cointegration tests shows strong evidence of explosive behavior in the DJIA and S&P 500 data. Then, I applied a sup augmented Dickey-Fuller test to check for the existence of periodically collapsing bubbles in stock prices. Such bubbles are found in S&P data during the late 1990s. Employing econometric tests from the third chapter, I continue in the fourth chapter to examine whether bubbles exist in stock prices of conventional economic sectors on the New York Stock Exchange. The ‘old economy’ as a whole is not found to have bubbles. But, periodically collapsing bubbles are found in Material and Telecommunication Services sectors, and the Real Estate industry group.

Macroinvertebrate abundance in montane tropical streams of varying land-use, Ecuador

Despite the importance of tropical montane cloud forest streams, studies investigating aquatic communities in these regions are rare and knowledge on the driving factors of community structure is missing. The objectives of this study therefore were to understand how land-use influences habitat structure and macroinvertebrate communities in cloud forest streams of southern Ecuador. We evaluated these relationships in headwater streams with variable land cover, using multivariate statistics to identify relationships between key habitat variables and assemblage structure, and to resolve differences in composition among sites. Results show that shading intensity, substrate type and pH were the environmental parameters most closely related to variation in community composition observed among sites. In addition, macroinvertebrate density and partly diversity was lower in forested sites, possibly because the pH in forested streams lowered to almost 5 during spates. Standard bioindicator metrics were unable to detect the changes in assemblage structure between disturbed and forested streams. In general, our results indicate that tropical montane headwater streams are complex and heterogeneous ecosystems with low invertebrate densities. We also found that some amount of disturbance, i.e. patchy deforestation, can lead at least initially to an increase in macroinvertebrate taxa richness of these streams.

Data compilation on the biological response to ocean acidification: environmental and experimental context of data sets and related literature

The exponential growth of studies on the biological response to ocean acidification over the last few decades has generated a large amount of data. To facilitate data comparison, a data compilation hosted at the data publisher PANGAEA was initiated in 2008 and is updated on a regular basis (doi:10.1594/PANGAEA.149999). By January 2015, a total of 581 data sets (over 4 000 000 data points) from 539 papers had been archived. Here we present the developments of this data compilation five years since its first description by Nisumaa et al. (2010). Most of study sites from which data archived are still in the Northern Hemisphere and the number of archived data from studies from the Southern Hemisphere and polar oceans are still relatively low. Data from 60 studies that investigated the response of a mix of organisms or natural communities were all added after 2010, indicating a welcomed shift from the study of individual organisms to communities and ecosystems. The initial imbalance of considerably more data archived on calcification and primary production than on other processes has improved. There is also a clear tendency towards more data archived from multifactorial studies after 2010. For easier and more effective access to ocean acidification data, the ocean acidification community is strongly encouraged to contribute to the data archiving effort, and help develop standard vocabularies describing the variables and define best practices for archiving ocean acidification data.

Sediment core-top GDGT data from the Arctic, the North Pacific and the Southern Ocean

TEX86 (TetraEther indeX of tetraethers consisting of 86 carbon atoms) is a sea surface temperature (SST) proxy based on the distribution of archaeal isoprenoid glycerol dialkyl glycerol tetraethers (GDGTs). In this study, we appraise the applicability of TEX86 and TEX86L in subpolar and polar regions using surface sediments. We present TEX86 and TEX86L data from 160 surface sediment samples collected in the Arctic, the Southern Ocean and the North Pacific. Most of the SST estimates derived from both TEX86 and TEX86L are anomalously high in the Arctic, especially in the vicinity of Siberian river mouths and the sea ice margin, plausibly due to additional archaeal contributions linked to terrigenous input. We found unusual GDGT distributions at five sites in the North Pacific. High GDGT-0/crenarchaeol and GDGT-2/crenarchaeol ratios at these sites suggest a substantial contribution of methanogenic and/or methanotrophic archaea to the sedimentary GDGT pool here. Apart from these anomalous findings, TEX86 and TEX86L values in the surface sediments from the Southern Ocean and the North Pacific do usually vary with overlaying SSTs. In these regions, the sedimentary TEX86-SST relationship is similar to the global calibration, and the derived temperature estimates agree well with overlaying annual mean SSTs at the sites. However, there is a systematic offset between the regional TEX86L-SST relationships and the global calibration. At these sites, temperature estimates based on the global TEX86L calibration are closer to summer SSTs than annual mean SSTs. This finding suggests that in these subpolar settings a regional TEX86L calibration may be a more suitable equation for temperature reconstruction than the global calibration.

Getting to the point: The influence of communicative intent on the kinematics of pointing gestures

Postprint

Left to right: Kim de Mutsert, Nicole Poret, and Sharon Ewe taking a break during sampling, Taylor Slough

This material is based upon work supported by the National Science Foundation through the Florida Coastal Everglades Long-Term Ecological Research program under Cooperative Agreements #DBI-0620409 and #DEB-9910514. This image is made available for non-commercial or educational use only.