A Monolithic Time Stretcher for Precision Time Recording

Identifying light mesons which contain only up/down quarks (pions) from those containing a strange quark (kaons) over the typical meter length scales of a particle physics detector requires instrumentation capable of measuring flight times with a resolution on the order of 20ps. In the last few years a large number of inexpensive, multi-channel Time-to-Digital Converter (TDC) chips have become available. These devices typically have timing resolution performance in the hundreds of ps regime. A technique is presented that is a monolithic version of ``time stretcher'' solution adopted for the Belle Time-Of-Flight system to address this gap between resolution need and intrinsic multi-hit TDC performance.Comment: 9 pages, 15 figures, minor corrections made, to appear as JINST_008

Ecological Insights for Freshwater Birds from Endoparasite Community Analysis

Birds are often considered some of the top organisms in freshwater food webs, but their specific ecological niches have remained relatively unstudied. Upper-level predators are often more susceptible to mortality from parasitism than direct predation. However, little is known about the parasite communities that inhabit these upper-level freshwater birds. To address this knowledge gap, we examined endoparasite communities in ten waterbird species: common loon (Gavia immer, n=14); American coot (Fulica americana, n=5); common moorhen (Gallinula chloropus, n=5); limpkin (Aramus guarauna, n=2); belted kingfisher (Megaceryle alcyon, n=6), red-breasted merganser (Mergus serrator, n=3); anhinga (Anhinga anhinga, n=3); pied-billed grebe (Podilymbus podiceps, n=2); least grebe (Tachybaptus dominicus, n=2); horned grebe (Podiceps auritus, n=2). Specimens were collected from local wildlife centers who froze them immediately post-mortem. These specimens were thawed overnight, and individual organ systems were examined visually for endoparasites. To date, we have recovered a total of 13,739 parasites, including 7,647 digenea, 5,296 cestodes, 286 acanthocephalans, and 510 nematodes. New host records of trematodes, nematodes, cestodes, and acanthocephalans are reported for least grebes and horned grebes in Florida. Understanding the parasite communities in these bird species allows for further analysis of the long-term diet preferences of these species in the South Florida area as well as possible migratory behavior of these bird taxa

Trophic Ecology and Parasitism of a Mesopelagic Fish Assemblage

Mesopelagic (open ocean, 200-1000 m daytime depth) fishes are important consumers of zooplankton and are prey of oceanic predators. Some mesopelagic fishes (e.g. lanternfishes and dragonfishes) undertake a diel vertical migration where they ascend to the near-surface waters during the night to feed and descend into the depths during the day to avoid predators. Other mesopelagic fishes (e.g. Sternoptyx spp.) do not vertically migrate and remain at deep depths throughout the day. While in the epipelagic zone (surface – 200 m depth), vertically-migrating fishes can become prey to upper-trophic level predators, such as: tunas and billfishes. Demersal fishes (e.g. rattails) often vertically-migrate as well, ascending into the pelagic zone to feed on holoplanktonic organisms. Hypothetically, a connection between the surface and the benthos can exist if migratory patterns overlap. Fishes of different depths and vertical migration habit likely have a different ecological role in the food web. The relationship between parasites and gut contents provides insights into ecological processes occurring within assemblages, as prey items are often vectors for parasites. This study examined the differences between the prey contents and parasites of 26 mesopelagic fish species in the Gulf of Mexico. Results showed that based on the proportionally dominant prey items per species, six main feeding strategies were differentiated within in this assemblage: copepodivores, copepods and other zooplankton, copepods and euphausiids, gelatinivores, generalists, shrimpivores, and upper-trophic level predators. Larger fishes preyed on larger prey items and harbored more parasites. An ontogenetic diet shift was detected for Sigmops elongatus at 75 mm standard length, progressing from eating primarily copepods at small sizes to eating primarily euphausiids at large sizes. Compared to similar studies, this study revealed a preponderance of trematodes, an endoparasite (parasite within the host) class often restricted to nearshore hosts. Helicometrina nimia, the dominant parasite of the snake mackerel Nealotus tripes, has not previously been recorded in hosts below 200 m depth, suggesting a food-web pathway that transitions from nearshore to offshore. These data can be used to develop and refine models aimed at understanding ecosystem structure and resilience to large-scale disturbances such as the Deepwater Horizon oil spill