Correlated Resource Models of Internet End Hosts

Understanding and modelling resources of Internet end hosts is essential for the design of desktop software and Internet-distributed applications. In this paper we develop a correlated resource model of Internet end hosts based on real trace data taken from the SETI@home project. This data covers a 5-year period with statistics for 2.7 million hosts. The resource model is based on statistical analysis of host computational power, memory, and storage as well as how these resources change over time and the correlations between them. We find that resources with few discrete values (core count, memory) are well modeled by exponential laws governing the change of relative resource quantities over time. Resources with a continuous range of values are well modeled with either correlated normal distributions (processor speed for integer operations and floating point operations) or log-normal distributions (available disk space). We validate and show the utility of the models by applying them to a resource allocation problem for Internet-distributed applications, and demonstrate their value over other models. We also make our trace data and tool for automatically generating realistic Internet end hosts publicly available

On the anatomy and phylogeny of the Zoarcidae (teleostei: perciformes)

The eelpouts, Zoarcidae, are a group of bony fishes, most species of which inhabit continental shelves and slopes of boreal seas. There are about 200 species of eelpouts, most of which are rare in collections, thus they have been only cursorially studied by most workers. as a result, the systematics of the family is in a poor state. This work is a contribution to the improvement of that state. The anatomy of all nominal genera of Zoarcidae was studied in an attempt to reconstruct phylogeny and establish the limits of genera. From analysis of a matrix of 63 characters, the 43 nominal genera recognized here form two subfamilies. One, Lycozoarcinae, contains only the primitive Lycozoarces regani. The other, Zoarcinae, is divided into three tribes, Zoarcini, Gymnelini and Lycodini. The more primitive zoarcids are characterized by having 4-6 suborbital bones arranged in a circular pattern close to the orbit, and complete cephalic lateralis pore patterns, except some of the few deep-sea forms. The more derived zoarcids are characterized by the loss of the interorbital pore (except for a few reversals) and by having 6-11 suborbital bones arranged in an L-shaped pattern away from the orbit (except a few which have lost some bones). An hypothesis is presented for the sister group relationship of Zoarcidae with six zoarceoid families: Ptilichthyidae, Zaproridae, Anarhichantidae, Stichaeidae, Pholididae and Scytalinidae. Bathymasteridae is hypothesized to be the primitive sister group of all the above taxa. The zoarceoids are probably most closely related to notothenioids and some of the trachinoids than to blennioids, a group recently restricted to six tropical-subtropical families. Since fully 45% of the genera recognized here are known from less than 15 specimens each, zoogeographic patterns are unsatisfactorily resolved. Considering the known distributions of all zoarcid genera, the highest endemism is found in temperate South America (30%), the northwestern Pacific (23%) and northeastern Pacific (11%). The best known deep-sea genera and species are wide-ranging, this perhaps due to the benthic, precocious larvae of most species

Accurate Noise Projection for Reduced Stochastic Epidemic Models

We consider a stochastic Susceptible-Exposed-Infected-Recovered (SEIR) epidemiological model. Through the use of a normal form coordinate transform, we are able to analytically derive the stochastic center manifold along with the associated, reduced set of stochastic evolution equations. The transformation correctly projects both the dynamics and the noise onto the center manifold. Therefore, the solution of this reduced stochastic dynamical system yields excellent agreement, both in amplitude and phase, with the solution of the original stochastic system for a temporal scale that is orders of magnitude longer than the typical relaxation time. This new method allows for improved time series prediction of the number of infectious cases when modeling the spread of disease in a population. Numerical solutions of the fluctuations of the SEIR model are considered in the infinite population limit using a Langevin equation approach, as well as in a finite population simulated as a Markov process.Comment: 38 pages, 10 figures, new title, Final revision to appear in Chao

Particulate and water-soluble carbon measured in recent snow at Summit, Greenland

Water-soluble organic carbon (WSOC), waterinsoluble particulate organic carbon (WIOC), and particulate elemental carbon (EC) were measured simultaneously for the first time on the Greenland Ice Sheet in surface snow and in a 3-meter snow pit. Snow pit concentrations reveal that, on average, WSOC makes up the majority (89%) of carbonaceous species, followed by WIOC (10%) and EC (1%). The enhancement of OC relative to EC (ratio 99:1) in Greenland snow suggests that, along with atmospheric particulate matter, gaseous organics contribute to snow-phase OC. Comparison of summer surface snow concentrations in 2006 with past summer snow pit layers (2002 – 2005) found a significant depletion in WSOC (20 – 82%) and WIOC (46 – 65%) relative to EC for 3 of the 4 years. The apparent substantial loss of WSOC and WIOC in aged snow suggests that post-depositional processes, such as photochemical reactions, need to be considered in linking ice core records of organics to atmospheric concentrations. Citation: Hagler, G. S. W., M. H. Bergin, E. A. Smith, J. E. Dibb, C. Anderson, and E. J. Steig (2007), Particulate and water-soluble carbon measured in recent snow at Summit, Greenland, Geophys. Res. Lett., 34, L16505, doi:10.1029/2007GL030110

Ichthyological Bulletin of the J.L.B. Smith Institute of Ichthyology; No. 55

New data on the eelpouts of the Magellan Province of South America are presented to include accounts of 10 of the 25 species presently known from the area. Aiakas zini, a second species for Aiakas Gosztonyi, 1977, is described as new. On the basis of material collected since the authors last published on the eelpouts of this region (1977 and 1988), enhanced descriptions are provided for Aiakas kreffti, Crossostomus chilensis, Lycenchelys bachmanni, Notolycodes schmidti, Oidiphoms brevis, Ophthalmolycus macrops and Pogonolycus marinae. Placed in synonymy are Crossostomus sobrali Lloris and Rucabado, 1987 with C. chilensis Regan, 1913, Iluocoetes facali Lloris and Rucabado, 1987 with I.fim- briatus Jenyns, 1842 and Haushia Lloris, 1988 with Pogonolycus Norman, 1937. Shorter accounts are provided for data from new specimens of Lycodonus malvinensis and Piedrabuenia ringueleti. A key to all of the species of Zoarcidae from the Magellan Province is included.Rhodes University Libraries (Digitisation

Ichthyological Bulletin of the J.L.B. Smith Institute of Ichthyology; No. 70

Deep-sea anglerfishes (Lophiiformes, Ceratioidei) of the familes Caulophrynidae, Melanocetidae, Himantolophidae, Diceratiidae, Oneirodidae, Thaumatichthyidae, Centrophrynidae, Ceratiidae, Gigantactinidae and Linophrynidae from southern Africa are reviewed since the publication of the book Smiths’ Sea Fishes (1986, 1991). Twenty-three new records of ceratioid anglerfishes are reported for the region, bringing the total to 32. No new taxa are described. The faunal area for southern African deep-sea fishes is expanded from that of Smiths’ Sea Fishes in order to include several literature records and recognize the broad distributions of these fishes through the deep-pelagic Atlantic/Indo-Pacific transit zone. Keys to all families, genera and species, as well as descriptions of all southern African specimens, are provided. The bulk of this material was collected during research cruises of South Africa’s RS AFRICANA and MEIRING NAUDE.Rhodes University Libraries (Digitisation

A new species of Pachycara Zugmayer, 1911 (Teleostei: Zoarcidae) from deep-sea chemosynthetic environments in the Caribbean Sea.

The 28th species of the eelpout genus Pachycara Zugmayer, 1911, is described from specimens collected from an active hydrothermal vent field at a depth of about 2300 m at the Mid-Cayman Spreading Centre of the Caribbean Sea. A tentatively identified early juvenile is recorded at a methane seep at a depth of 1049 m near Tobago. The new species is distinguished from its congeners mainly by its few pectoral fin rays, low vertebral counts, single, mediolateral branch of the lateral line system and presence of scales on the nape and cheeks