The fish fauna of the Iwokrama Forest

Fishes were collected from the rivers in and around the Iwokrama Forest during January-February and November-December 1997. Four hundred species of fish were recorded from forty families in ten orders. Many of these fishes are newly recorded from Guyana and several are thought to be endemic. The number of species recorded for the area is surprising given the low level of effort and suggests that this area may be particularly important from a fish diversity perspective. This paper focuses on species of particular interest from a management perspective including those considered economically important, rare or endangered. The paper is also the basis for developing fisheries management systems in the Iwokrama Forest and Rupununi Wetlands

No arbitrage and closure results for trading cones with transaction costs

In this paper, we consider trading with proportional transaction costs as in Schachermayer’s paper (Schachermayer in Math. Finance 14:19–48, 2004). We give a necessary and sufficient condition for ${\mathcal{A}}$ , the cone of claims attainable from zero endowment, to be closed. Then we show how to define a revised set of trading prices in such a way that, firstly, the corresponding cone of claims attainable for zero endowment, ${\tilde{ {\mathcal{A}}}}$ , does obey the fundamental theorem of asset pricing and, secondly, if ${\tilde{ {\mathcal{A}}}}$ is arbitrage-free then it is the closure of ${\mathcal{A}}$ . We then conclude by showing how to represent claims

Transits and Occultations of an Earth-Sized Planet in an 8.5-Hour Orbit

We report the discovery of an Earth-sized planet ($1.16\pm 0.19 R_\oplus$) in an 8.5-hour orbit around a late G-type star (KIC 8435766, Kepler-78). The object was identified in a search for short-period planets in the {\it Kepler} database and confirmed to be a transiting planet (as opposed to an eclipsing stellar system) through the absence of ellipsoidal light variations or substantial radial-velocity variations. The unusually short orbital period and the relative brightness of the host star ($m_{\rm Kep}$ = 11.5) enable robust detections of the changing illumination of the visible hemisphere of the planet, as well as the occultations of the planet by the star. We interpret these signals as representing a combination of reflected and reprocessed light, with the highest planet dayside temperature in the range of 2300 K to 3100 K. Follow-up spectroscopy combined with finer sampling photometric observations will further pin down the system parameters and may even yield the mass of the planet.Comment: Accepted for publication, ApJ, 10 pages and 6 figure

Finite-Size Scaling of the Domain Wall Entropy Distributions for the 2D ±J\pm J Ising Spin Glass

The statistics of domain walls for ground states of the 2D Ising spin glass with +1 and -1 bonds are studied for $L \times L$ square lattices with $L \le 48$, and $p$ = 0.5, where $p$ is the fraction of negative bonds, using periodic and/or antiperiodic boundary conditions. When $L$ is even, almost all domain walls have energy $E_{dw}$ = 0 or 4. When $L$ is odd, most domain walls have $E_{dw}$ = 2. The probability distribution of the entropy, $S_{dw}$, is found to depend strongly on $E_{dw}$. When $E_{dw} = 0$, the probability distribution of $|S_{dw}|$ is approximately exponential. The variance of this distribution is proportional to $L$, in agreement with the results of Saul and Kardar. For $E_{dw} = k > 0$ the distribution of $S_{dw}$ is not symmetric about zero. In these cases the variance still appears to be linear in $L$, but the average of $S_{dw}$ grows faster than $\sqrt{L}$. This suggests a one-parameter scaling form for the $L$-dependence of the distributions of $S_{dw}$ for $k > 0$.Comment: 13 page

SubmilliJansky Transients in Archival Radio Observations

[ABRIDGED] We report the results of a 944-epoch survey for transient sources with archival data from the Very Large Array spanning 22 years with a typical epoch separation of 7 days. Observations were obtained at 5 or 8.4 GHz for a single field of view with a full-width at half-maximum of 8.6' and 5.1', respectively, and achieved a typical point-source detection threshold at the beam center of ~300 microJy per epoch. Ten transient sources were detected with a significance threshold such that only one false positive would be expected. Of these transients, eight were detected in only a single epoch. Two transients were too faint to be detected in individual epochs but were detected in two-month averages. None of the ten transients was detected in longer-term averages or associated with persistent emission in the deep image produced from the combination of all epochs. The cumulative rate for the short timescale radio transients above 370 microJy at 5 and 8.4 GHz is 0.07 < R < 40 deg^-2 yr^-1, where the uncertainty is due to the unknown duration of the transients, 20 min < t_char < 7 days. A two-epoch survey for transients will detect 1.5 +/- 0.4 transient per square degrees above a flux density of 370 microJy. Two transients are associated with galaxies at z=0.040 and z=0.249. These may be similar to the peculiar Type Ib/c radio supernova SN 1998bw associated with GRB 980428. Six transients have no counterparts in the optical or infrared (R=27, Ks=18). The hosts and progenitors of these transients are unknown.Comment: Accepted for ApJ; full quality figures available at http://astro.berkeley.edu/~gbower/ps/rt.pd

Natural products improve healthspan in aged mice and rats: a systematic review and meta-analysis

Over the last decades a decrease in mortality has paved the way for late onset pathologies such as cardiovascular, metabolic or neurodegenerative diseases. This evidence has led many researchers to shift their focus from researching ways to extend lifespan to finding ways to increase the number of years spent in good health; “healthspan” is indeed the emerging concept of such quest for ageing without chronic or disabling diseases and dysfunctions. Regular consumption of natural products might improve healthspan, although the mechanisms of action are still poorly understood. Since preclinical studies aimed to assess the efficacy and safety of these compounds are growing, we performed a systematic review and meta-analysis on the effects of natural products on healthspan in mouse and rat models of physiological ageing. Results indicate that natural compounds show robust effects improving stress resistance and cognitive abilities. These promising data call for further studies investigating the underlying mechanisms in more depth

Finite-Size Scaling in the Energy-Entropy Plane for the 2D +- J Ising Spin Glass

For $L \times L$ square lattices with $L \le 20$ the 2D Ising spin glass with +1 and -1 bonds is found to have a strong correlation between the energy and the entropy of its ground states. A fit to the data gives the result that each additional broken bond in the ground state of a particular sample of random bonds increases the ground state degeneracy by approximately a factor of 10/3. For $x = 0.5$ (where $x$ is the fraction of negative bonds), over this range of $L$, the characteristic entropy defined by the energy-entropy correlation scales with size as $L^{1.78(2)}$. Anomalous scaling is not found for the characteristic energy, which essentially scales as $L^2$. When $x= 0.25$, a crossover to $L^2$ scaling of the entropy is seen near $L = 12$. The results found here suggest a natural mechanism for the unusual behavior of the low temperature specific heat of this model, and illustrate the dangers of extrapolating from small $L$.Comment: 9 pages, two-column format; to appear in J. Statistical Physic

The Pediatric Quality of Life Inventory™ (PedsQL™) family impact module: reliability and validity of the Brazilian version

This is an Open Access article distributed under the terms of the Creative Commons Attribution Licens

The Politics of Commerce : The Congress of Chambers of Commerce of the Empire, 1886-1914

Peer reviewedPublisher PD

Comparative Genomics of Carriage and Disease Isolates of Streptococcus pneumoniae Serotype 22F Reveals Lineage-Specific Divergence and Niche Adaptation

Streptococcus pneumoniae is a major cause of meningitis, sepsis, and pneumonia worldwide. Pneumococcal conjugate vaccines have been part of the United Kingdom’s childhood immunization program since 2006 and have significantly reduced the incidence of disease due to vaccine efficacy in reducing carriage in the population. Here we isolated two clones of 22F (an emerging serotype of clinical concern, multilocus sequence types 433 and 698) and conducted comparative genomic analysis on four isolates, paired by Sequence Type (ST) with one of each pair being derived from carriage and the other disease (sepsis). The most compelling observation was of nonsynonymous mutations in pgdA, encoding peptidoglycan N-acetylglucosamine deacetylase A, which was found in the carriage isolates of both ST433 and 698. Deacetylation of pneumococcal peptidoglycan is known to enable resistance to lysozyme upon invasion. Althought no other clear genotypic signatures related to disease or carriage could be determined, additional intriguing comparisons between the two STs were possible. These include the presence of an intact prophage, in addition to numerous additional phage insertions, within the carriage isolate of ST433. Contrasting gene repertoires related to virulence and colonization, including bacteriocins, lantibiotics, and toxin-–antitoxin systems, were also observed