Cyclone Codes

We introduce Cyclone codes which are rateless erasure resilient codes. They combine Pair codes with Luby Transform (LT) codes by computing a code symbol from a random set of data symbols using bitwise XOR and cyclic shift operations. The number of data symbols is chosen according to the Robust Soliton distribution. XOR and cyclic shift operations establish a unitary commutative ring if data symbols have a length of $p-1$ bits, for some prime number $p$. We consider the graph given by code symbols combining two data symbols. If $n/2$ such random pairs are given for $n$ data symbols, then a giant component appears, which can be resolved in linear time. We can extend Cyclone codes to data symbols of arbitrary even length, provided the Goldbach conjecture holds. Applying results for this giant component, it follows that Cyclone codes have the same encoding and decoding time complexity as LT codes, while the overhead is upper-bounded by those of LT codes. Simulations indicate that Cyclone codes significantly decreases the overhead of extra coding symbols

Projected sea level rise and the conservation ecology of the Micronesian Megapode (Megapodius laperouse senex) in Palau, Micronesia

Climate change has been a subject of numerous studies. While findings suggest that most biological taxa will be affected by its manifestations, aspects of a species life history may increase its susceptibility to climate change. Given their reliance on environmental sources of heat to incubate their eggs, I examined the vulnerability to climate change of the avian family Megapodiidae. I also assessed habitat use, susceptibility to sea level rise, and the effect of introduced rats and tourist presence, as added stressors to climate change, on the Micronesian Megapode (Megapodius laperouse senex) in Palau. Based on available literature, I employed a trait-based assessment to investigate the vulnerability of 21 species of megapodes to climate change. All species were predicted to experience at least a 2°C increase in mean annual temperature, 12 may experience a moderate or greater fluctuation in rainfall, and 16 would be exposed to rising seas. While the most vulnerable megapodes are intrinsically rare and range restricted, mound nesting species may be more resilient to climate change than others. I examined breeding and foraging habitat use by the mound nesting megapode in the Rock Islands Southern Lagoon Conservation Area (RISL), where it almost exclusively uses low-lying littoral strand habitat for breeding. Megapodes preferentially selected sites that were 1) relatively close to shore, 2) contained large trees, and 3) exhibited greater canopy heights than the surrounding forest. The subspecies foraged in a non-preferential manner and used all littoral habitat with no apparent influence of dominant plant species composition. Using GIS and the latest spatial data, I modelled the effect of three currently accepted scenarios (0.52 m, 0.98 m, and 1.9 m) of sea level rise on their known breeding habitat. The RISL is comprised of 3,857.5 ha of forested cover of which megapodes used 120.8 ha (3.1%) for breeding, with an additional 25.3 ha potentially available to them. Megapodes may lose at least 32.5% to 43.3% of known breeding habitat and 25.7% to 31.3% of potential habitat to inundation, respectively. Using passive chew-tag and call playback surveys, I examined whether introduced rats and tourist presence may negatively affect megapodes in the RISL. Rat detection probability and site occupancy were significantly higher on tourist visited iv (89% and 99%, respectively) compared to tourist-free islands (52% and 73%). I detected significantly more megapodes at stations on tourist-free islands (93%) than tourist visited (47%), but relative abundance was not significantly different between island types. My findings suggested no significant relationship between rats and megapodes, a negative relationship between tourist presence and megapodes, and augmentation of rat populations by tourist presence. I compared the ecology of, and IUCN listed threats for, Micronesian Megapodes in Palau with those in the Mariana Islands. I proposed both the inclusion of an additional climate change related threat based on my sea level rise modelling, and new ranking of all IUCN threats by subspecies. Lastly, I proposed research and data acquisition priorities necessary to fill current gaps in the knowledge of megapodes in Palau and facilitate its long-term conservation