Optimal packing for cascaded regenerative transmission based on phase sensitive amplifiers

We investigate the transmission performance of advanced modulation formats in nonlinear regenerative channels based on cascaded phase sensitive amplifiers. We identify the impact of amplitude and phase noise dynamics along the transmission line and show that after a cascade of regenerators, densely packed single ring PSK constellations outperform multi-ring constellations. The results of this study will greatly simplify the design of future nonlinear regenerative channels for ultra-high capacity transmission

Optimal packing for cascaded regenerative transmission based on phase sensitive amplifiers

We investigate the transmission performance of advanced modulation formats in nonlinear regenerative channels based on cascaded phase sensitive amplifiers. We identify the impact of amplitude and phase noise dynamics along the transmission line and show that after a cascade of regenerators, densely packed single ring PSK constellations outperform multi-ring constellations. The results of this study will greatly simplify the design of future nonlinear regenerative channels for ultra-high capacity transmission. © 2013 Optical Society of America.

Efficient packing for phase regenerative channels

We compare the performance of advanced modulation formats in cascaded phase regenerative systems and demonstrate the importance of constellation optimization to the transfer function characteristics of the regenerator. © 2013 IEEE.

Tom Riley and Althea Silvera Packing the Charles Perry Papers

This photo shows Betty Perry, Tom Riley, and Althea Silvera in the floor packingthe Charles Perry Papers in the Perry Palm Beach home. Charles Perry donated his papers of his time as president of the university to the FIU library where they are held in the archives. An interview, filmed by Richard Pabon and Elizabeth Marsh from FIU’s Broadcast Video Production team, recorded this event. Charles Edward Perry (Chuck), 1937-1999, was the founding president of Florida International University in Miami, Florida. He grew up in Logan County, West Virginia and received his bachelor's and masters's degrees from Bowling Green State University. He married Betty Laird in 1961. In 1969, at the age of 32, Perry was the youngest president of any university in the nation. The name of the university reflects Perry’s desire for a title that would not limit the scope of the institution and would support his vision of having close ties to Latin America. Perry and a founding corps opened FIU to 5,667 students in 1972 with only one large building housing six different schools. Perry left the office of President of FIU in 1976 when the student body had grown to 10,000 students and the university had six buildings, offered 134 different degrees and was fully accredited. Charles Perry died on August 30, 1999 at his home in Rockwall, Texas. He is buried on the FIU campus in front of the Graham Center entrance.

Restaurant Customer Loyalty: A Qualitative Assessment of Niche Brands

Using the Loyalty Triangle framework developed by Lewis and Shoemaker (1999) and focus group methodology, the study examined how a niche brand restaurant best achieved long-term loyalty. Results indicate that customers are loyal to a niche brand because of the unique characteristics inherent to the brand. Customers have higher perceptions of such qualities as the presentation of service, consistency of product, and the benefits offered by the loyalty program than characteristics that are shared across all brands. Niche brand restaurants can be more effective in developing these qualities to promote customer loyalty.

Relative roles of dispersal dynamics and competition in determining the isotopic niche breadth of a wetland fish

1. The niche variation hypothesis predicts that among-individual variation in niche use will increase in the presence of intraspecific competition and decrease in the presence of interspecific competition. We sought to determine whether the local isotopic niche breadth of fish inhabiting a wetland was best explained by competition for resources and the niche variation hypothesis, by dispersal of individuals from locations with different prey resources or by a combination of the two. We analysed stable isotopes of carbon and nitrogen as indices of feeding niche and compared metrics of within-site spread to characterise site-level isotopic niche breadth. We then evaluated the explanatory power of competing models of the direct and indirect effects of several environmental variables spanning gradients of disturbance, competition strength and food availability on among-individual variation of the eastern mosquitofish (Gambusia holbrooki). 2. The Dispersal model posits that only the direct effect of disturbance (i.e. changes in water level known to induce fish movement) influences among-individual variation in isotopic niche. The Partitioning model allows for only direct effects of local food availability on among-individual variation. The Combined model allows for both hypotheses by including the direct effects of disturbance and food availability. 3. A linear regression of the Combined model described more variance than models limited to the variables of either the Dispersal or Partitioning models. Of the independent variables considered, the food availability variable (per cent edible periphyton) explained the most variation in isotopic niche breadth, followed closely by the disturbance variable (days since last drying event). 4. Structural equation modelling provided further evidence that the Combined model was best supported by the data, with the Partitioning and the Dispersal models only modestly less informative. Again, the per cent edible periphyton was the variable with the largest direct effect on niche variability, with other food availability variables and the disturbance variable only slightly less important. Indirect effects of heterospecific and conspecific competitor densities were also important, through their effects on prey density. 5. Our results support the Combined hypotheses, although partitioning mechanisms appear to explain the most diet variation among individuals in the eastern mosquitofish. The results also support some predictions of the niche variation hypothesis, although both conspecific and interspecific competition appeared to increase isotopic niche breadth in contrast to predictions that interspecific competition would decrease it. We think this resulted from high diet overlap of co-occurring species, most of which consume similar macroinvertebrates.

Latitudinal shift in thermal niche breadth results from thermal release during a climate-mediated range expansion

Funded by Biodiversity and Ecosystem Services in a Changing Climate Wenner-Gren Foundation Swedish Research Council The Royal Swedish Academy of Sciences Stiftelsen Anna-Greta Holger Crafoords Fund The Crafoord Foundation

Latitudinal shift in thermal niche breadth results from thermal release during a climate-mediated range expansion

Funded by Biodiversity and Ecosystem Services in a Changing Climate Wenner-Gren Foundation Swedish Research Council The Royal Swedish Academy of Sciences Stiftelsen Anna-Greta Holger Crafoords Fund The Crafoord Foundation

Model updating using genetic algorithms with sequential niche technique

The authors would like to express their gratitude to organizations and people that supported this research. Piotr Omenzetter’s work within the Lloyd’s Register Foundation Centre for Safety and Reliability Engineering at the University of Aberdeen is supported by Lloyd’s Register Foundation. The Foundation helps to protect life and property by supporting engineering-related education, public engagement and the application of research. Ben Ryder of Aurecon and Graeme Cummings of HEB Construction assisted in obtaining access to the bridge and information for modelling. Luke Williams and Graham Bougen, undergraduate research students, assisted with testing.

Latitudinal shift in thermal niche breadth results from thermal release during a climate-mediated range expansion

Funded by Biodiversity and Ecosystem Services in a Changing Climate Wenner-Gren Foundation Swedish Research Council The Royal Swedish Academy of Sciences Stiftelsen Anna-Greta Holger Crafoords Fund The Crafoord Foundation

Family packing car for camping trip

Inscriptions: Verso: [stamped] Photograph by Freda Leinwand. [463 West Street, Studio 229G, New York, NY 10014].

Modelled niche centres and niche breadths of open ocean phytoplankton taxa

This data contains realized ecological niche estimates of phytoplankton taxa within the mixed layer of the open ocean. The estimates are based on data from the MARine Ecosystem DATa (MAREDAT) initiative, and cover five phytoplankton functional types: coccolithophores (40 species), diatoms (87 species), diazotrophs (two genera), Phaeocystis (two species) and picophytoplankton (two genera). Considered as major niche dimensions were temperature (°C), mixed layer depth (MLD; m), nitrate concentration (µmoles/L), mean photosynthetically active radiation in the mixed layer (MLPAR; µmoles/m**2/s), salinity, and the excess of phosphate versus nitrate relative to the Redfield ratio (P*; µmoles/L). For each niche dimension at a time, conditions at presence locations of the taxa were contrasted with conditions in 12 000 randomly sampled points from the open ocean using MaxEnt models. We used the quartiles of the response curves of these models to parameterize realized niche centers and niche breadths: the median (q50) of the response curves was considered to be the niche center and the distance between the lower quartile (q25) and the upper quartile (q75) was used as a rough estimate of niche breadth. We only reported meaningful niche estimates, i.e., estimates based on MaxEnt models that perform significantly better than random, as indicated by an area under the curve (AUC) score significantly larger than 0.5.

Evolution of lactase persistence: an example of human niche construction

Niche construction is the process by which organisms construct important components of their local environment in ways that introduce novel selection pressures. Lactase persistence is one of the clearest examples of niche construction in humans. Lactase is the enzyme responsible for the digestion of the milk sugar lactose and its production decreases after the weaning phase in most mammals, including most humans. Some humans, however, continue to produce lactase throughout adulthood, a trait known as lactase persistence. In European populations, a single mutation (−13910*T) explains the distribution of the phenotype, whereas several mutations are associated with it in Africa and the Middle East. Current estimates for the age of lactase persistence-associated alleles bracket those for the origins of animal domestication and the culturally transmitted practice of dairying. We report new data on the distribution of −13910*T and summarize genetic studies on the diversity of lactase persistence worldwide. We review relevant archaeological data and describe three simulation studies that have shed light on the evolution of this trait in Europe. These studies illustrate how genetic and archaeological information can be integrated to bring new insights to the origins and spread of lactase persistence. Finally, we discuss possible improvements to these models.

Modelling the niche for a marine vertebrate: A case study incorporating behavioural plasticity, proximate threats and climate change

[EN] The integration of satellite telemetry, remotely sensed environmental data, and habitat/environmental modelling has provided for a growing understanding of spatial and temporal ecology of species of conservation concern. The Republic of Cape Verde comprises the only substantial rookery for the loggerhead turtle Caretta caretta in the eastern Atlantic. A size related dichotomy in adult foraging patterns has previously been revealed for adult sea turtles from this population with a proportion of adults foraging neritically, whilst the majority forage oceanically. Here we describe observed habitat use and employ ecological niche modelling to identify suitable foraging habitats for animals utilising these two distinct behavioural strategies. We also investigate how these predicted habitat niches may alter under the influence of climate change induced oceanic temperature rises.