Characterization of novel beta-galactosidase activity that contributes to glycoprotein degradation and virulence in Streptococcus pneumoniae.

The pneumococcus obtains its energy from the metabolism of host glycosides. Therefore, efficient degradation of host glycoproteins is integral to pneumococcal virulence. In search of novel pneumococcal glycosidases, we characterized the Streptococcus pneumoniae strain D39 protein encoded by SPD_0065 and found that this gene encodes a beta-galactosidase. The SPD_0065 recombinant protein released galactose from desialylated fetuin, which was used here as a model of glycoproteins found in vivo. A pneumococcal mutant with a mutation in SPD_0065 showed diminished beta-galactosidase activity, exhibited an extended lag period in mucin-containing defined medium, and cleaved significantly less galactose than the parental strain during growth on mucin. As pneumococcal beta-galactosidase activity had been previously attributed solely to SPD_0562 (bgaA), we evaluated the contribution of SPD_0065 and SPD_0562 to total beta-galactosidase activity. Mutation of either gene significantly reduced enzymatic activity, but beta-galactosidase activity in the double mutant, although significantly less than that in either of the single mutants, was not completely abolished. The expression of SPD_0065 in S. pneumoniae grown in mucin-containing medium or tissues harvested from infected animals was significantly upregulated compared to that in pneumococci from glucose-containing medium. The SPD_0065 mutant strain was found to be attenuated in virulence in a manner specific to the host tissue

Estimating entanglement of unknown states

The experimental determination of entanglement is a major goal in the quantum information field. In general the knowledge of the state is required in order to quantify its entanglement. Here we express a lower bound to the robustness of entanglement of a state based only on the measurement of the energy observable and on the calculation of a separability energy. This allows the estimation of entanglement dismissing the knowledge of the state in question.Comment: 3 pages, 1 figure. Comments welcome. V2: references updated. Accepted version by Applied Physics Letter

Orbital Magnetism in Ensembles of Parabolic Potentials

We study the magnetic susceptibility of an ensemble of non-interacting electrons confined by parabolic potentials and subjected to a perpendicular magnetic field at finite temperatures. We show that the behavior of the average susceptibility is qualitatively different from that of billiards. When averaged over the Fermi energy the susceptibility exhibits a large paramagnetic response only at certain special field values, corresponding to comensurate classical frequencies, being negligible elsewhere. We derive approximate analytical formulae for the susceptibility and compare the results with numerical calculations.Comment: 4 pages, 4 figures, REVTE

GRB 070518: A Gamma-ray Burst with Optically Dim Luminosity

We present our optical observations of {\em Swift} GRB 070518 afterglow obtained at the 0.8-m Tsinghua University-National Astronomical Observatory of China telescope (TNT) at Xinglong Observatory. Our follow-up observations were performed from 512 sec after the burst trigger. With the upper limit of redshift $\sim$0.7, GRB 070518 is found to be an optically dim burst. The spectra indices $\beta_{ox}$ of optical to X-ray are slightly larger than 0.5, which implies the burst might be a dark burst. The extinction $A_{V}$ of the host galaxy is 3.2 mag inferred from the X-ray hydrogen column density with Galactic extinction law, and 0.3 mag with SMC extinction law. Also, it is similar to three other low-redshift optically dim bursts, which belong to XRR or XRF, and mid-term duration($T_{90}<10$, except for GRB 070419A, $T_{90}$=116s). Moreover, its $R$ band afterglow flux is well fitted by a single power-law with an index of 0.87. The optical afterglow and the X-ray afterglow in the normal segment might have the same mechanism, as they are consistent with the prediction of the classical external shock model. Besides, GRB 070518 agrees with Amati relation under reasonable assumptions. The Ghirlanda relation is also tested with the burst.Comment: 8 pages, 4 figures, MNRAS accepte

The Rapidly Flaring Afterglow of the Very Bright and Energetic GRB 070125

We report on multi-wavelength observations, ranging from the X-ray to radio wave bands, of the IPN-localized gamma-ray burst GRB 070125. Spectroscopic observations reveal the presence of absorption lines due to O I, Si II, and C IV, implying a likely redshift of z = 1.547. The well-sampled light curves, in particular from 0.5 to 4 days after the burst, suggest a jet break at 3.7 days, corresponding to a jet opening angle of ~7.0 degrees, and implying an intrinsic GRB energy in the 1 - 10,000 keV band of around E = (6.3 - 6.9)x 10^(51) erg (based on the fluences measured by the gamma-ray detectors of the IPN network). GRB 070125 is among the brightest afterglows observed to date. The spectral energy distribution implies a host extinction of Av < 0.9 mag. Two rebrightening episodes are observed, one with excellent time coverage, showing an increase in flux of 56% in ~8000 seconds. The evolution of the afterglow light curve is achromatic at all times. Late-time observations of the afterglow do not show evidence for emission from an underlying host galaxy or supernova. Any host galaxy would be subluminous, consistent with current GRB host-galaxy samples. Evidence for strong Mg II absorption features is not found, which is perhaps surprising in view of the relatively high redshift of this burst and the high likelihood for such features along GRB-selected lines of sight.Comment: 50 pages, 9 figures, 5 tables Accepted to the Astrophysical Journa

Large questions faced by education at the sharp end in SIDS

The paper reflects upon thirty years of collective experience relating to educational and environmental development in small states worldwide. Particular attention is given to what the international community can learn from the distinctive experience of small island developing states (SIDS), and how this relates to the big questions and contemporary global challenges faced worldwide. In doing so, insights from local experience, decolonial perspectives, and indigenous knowledges are highlighted for a multidisciplinary and international readership

Diverse Microbial Prey in the Guts of Gelatinous Grazers Revealed by Microscopy

Mucous mesh grazers including pelagic tunicates and thecosome pteropods play a key role in oceanic food webs. They are taxonomically and morphologically diverse and can be highly abundant. Using their fine mucous meshes, these pelagic grazers ingest a wide range of plankton prey and link pelagic and benthic marine ecosystems. Characterizing the diet of this group is central to fully understanding marine food webs and developing accurate food web models. However, gelatinous grazers are challenging to study owing to their physically delicate composition so studying their feeding ecology requires numerous complementary techniques. Microscopy has largely been supplanted by other methods, but it remains valuable for its precision in determining cell size and morphology, which are key to characterize the diet and feeding mechanics of grazers. We use environmental scanning electron microscopy (ESEM) to examine the gut contents of several mucous mesh grazers from the Northern California Current (NCC) including Dolioletta gegenbauri, Limacina helicina, Pegea socia, Pyrosoma atlanticum, and Thetys vagina. Our findings provide taxonomic resolution of the prey of these grazers, which includes dinoflagellates, silicoflagellates, centric and pennate diatoms, coccolithophores, tintinnids, foraminiferans, and copepods. Our results show that these gelatinous grazers ingest prey ranging in size from 0.4 µm to 91.0 µm and expands the known prey size range for Thetys vagina. This work underscores the advantages of using microscopy, including insights into prey morphology and integrity, which enhances our understanding of feeding selectivity, prey defenses, and the pathways of grazed plankton through the marine ecosystem

Dust and Metal Column Densities in Gamma-Ray Burst Host Galaxies

In this paper we present the results from the analysis of a sample of 28 gamma-ray burst (GRB) afterglow spectral energy distributions, spanning the X-ray through to near-infrared wavelengths. This is the largest sample of GRB afterglow spectral energy distributions thus far studied, providing a strong handle on the optical depth distribution of soft X-ray absorption and dust-extinction systems in GRB host galaxies. We detect an absorption system within the GRB host galaxy in 79% of the sample, and an extinction system in 71% of the sample, and find the Small Magellanic Cloud (SMC) extinction law to provide an acceptable fit to the host galaxy extinction profile for the majority of cases, consistent with previous findings. The range in the soft X-ray absorption to dust-extinction ratio, N_{H,X}/Av, in GRB host galaxies spans almost two orders of magnitude, and the typical ratios are significantly larger than those of the Magellanic Clouds or Milky Way. Although dust destruction could be a cause, at least in part, for the large N_{H,X}/Av ratios, the good fit provided by the SMC extinction law for the majority of our sample suggests that there is an abundance of small dust grains in the GRB environment, which we would expect to have been destroyed if dust destruction were responsible for the large N_{H,X}/Av ratios. Instead, our analysis suggests that the distribution of N_{H,X}/Av in GRB host galaxies may be mostly intrinsic to these galaxies, and this is further substantiated by evidence for a strong negative correlation between N_{H,X}/Av and metallicity for a subsample of GRB hosts with known metallicity. Furthermore, we find the N_{H,X}/Av ratio and metallicity for this subsample of GRBs to be comparable to the relation found in other more metal-rich galaxies.Comment: 23 pages, 10 figures, accepted for publication in MNRA

Information professionals and copyright literacy: a multinational study

Purpose: The purpose of this paper is to present findings from a multinational survey on copyright literacy of specialists from libraries and other cultural institutions. Design/methodology/approach: This paper is based on a multinational survey of copyright literacy competencies of Library and Information Science (LIS) professionals and those who work in the cultural heritage sector (archives and museums), conducted in 13 countries, namely Bulgaria (BG), Croatia (CR), Finland (FI), France (FR), Hungary (HU), Lithuania (LT), Mexico (MX), Norway (NO), Portugal (PT), Romania (RO), Turkey (TR), UK and USA in the period July 2013-March 2015. An online survey instrument was developed in order to collect data from professionals regarding their familiarity with, knowledge and awareness of, and opinions on copyright-related issues. Findings: Findings of this study highlight gaps in existing knowledge of copyright, and information about the level of copyright literacy of LIS and cultural sector professionals. Also attitudes toward copyright learning content in academic education and continuing professional development training programs are investigated. Originality/value: This study aimed to address a gap in the literature by encompassing specialists from the cultural institutions in an international comparative context. The paper offers guidance for further understanding of copyright in a wider framework of digital and information literacy; and for the implementation of copyright policy, and the establishment of copyright advisor positions in cultural institutions. The recommendations support a revision of academic and continuing education programs learning curriculum and methods