Evolution of Massive Haloes in non-Gaussian Scenarios

We have performed high-resolution cosmological N-body simulations of a concordance LCDM model to study the evolution of virialized, dark matter haloes in the presence of primordial non-Gaussianity. Following a standard procedure, departures from Gaussianity are modeled through a quadratic Gaussian term in the primordial gravitational potential, characterized by a dimensionless non-linearity strength parameter f_NL. We find that the halo mass function and its redshift evolution closely follow the analytic predictions of Matarrese et al.(2000). The existence of precise analytic predictions makes the observation of rare, massive objects at large redshift an even more attractive test to detect primordial non-Gaussian features in the large scale structure of the universe.Comment: 7 pages,3 figures, submitted to MNRA

Multimodel Analysis of the Atmospheric Response to Antarctic Sea Ice Loss at Quadrupled CO2

This is the author accepted manuscript. The final version is available from Wiley via the DOI in this recordAntarctic sea ice cover is projected to significantly decrease by the end of the twenty-first century if greenhouse gas concentrations continue to rise, with potential consequences for Southern Hemisphere weather and climate. Here we examine the atmospheric response to projected Antarctic sea ice loss at quadrupled CO2, inferred from 11 Coupled Model Intercomparison Project phase 5 models. Our study is the first multimodel analysis of the atmospheric response to Antarctic sea ice loss. Projected sea ice loss enhances the negative phase of the Southern Annular Mode, which slightly damps the positive Southern Annular Mode response to increased CO2, particularly in spring. The negative Southern Annular Mode response largely reflects a weakening of the eddy-driven jet, and to a lesser extent, an equatorward shift of the jet. Sea ice loss induces near-surface warming over the high-latitude Southern Ocean, but warming does not penetrate over the Antarctic continent. In spring, we find multimodel evidence for a weakened polar stratospheric vortex in response to sea ice loss.NER

Ecological fate and effects of solvent-refined-coal (SRC) materials: a status report

Non-occupational health effects associated with SRC operation will be determined by environmental factors governing the form, transport, and persistence of SRC materials and wastes - factors which also mediate exposure to man. Accordingly, the research described is an attempt to determine the fate of disposed solid wastes and spilled SRC materials, and it necessarily focuses on water soluble, persistent materials with greatest potential for mobility and incorporation into water and food supplies. Initially, aqueous equilibrations of SRC-II liquid material and SRC-I nongasified mineral residue were subjected to chemical characterization. Subsequently, laboratory studies were performed on the interaction of aqueous equilibrates of SRC-II liquid and SRC-I non-gasified mineral residue with soil materials isolated suspended sediments, and bottom sediments. These studies were designed to identify effects of specific sorption reactions ion or induced-ion exchange reactions, and toxicity of water soluble, biologically active materials derived from liquid and solid wastes. Results of these experiments have applicability to the environmental fate and effects of biologically active compounds released under different scenarios from product spills and solid waste disposal

Using Zebrafish to implement a Course-Based Undergraduate Research Experience (CURE) to study Teratogenesis in Two Biology Laboratory Courses

poster abstractAbstract: Two related course-based undergraduate research experiences (CUREs) were introduced into a freshman introductory biology and a sophomore level cell biology class. In fall 2013, first semester freshman students were introduced to scientific research in an introductory biology laboratory course. Students were mentored to develop and execute original research projects investigating embryonic nicotine and caffeine exposure effects on development, particularly on heart development and function, using zebrafish embryos. In spring 2014, sophomore level cell biology students extended these studies and analyzed the effects of nicotine and caffeine at precise times in gastrulation. The freshman research experience was repeated in fall 2014 where a new group of students expanded the earlier research to investigate effects of additional toxicants on development. Students designed new protocols, made measurements, documented data, presented results and generated novel, high quality preliminary data that will be further studied in successive semesters. Student researchers identified novel effects of nicotine exposure on gastrulation and heart morphogenesis. Student surveys showed the greatest gains in ability to (1) design experiments, (2) analyze data, and (3) make scientific presentations. This CURE approach generated excitement and engagement that translated into high student satisfaction and enhanced learning

A discovery down under: decoding the draft genome sequence of Pantoea stewartii from Australia's Critically Endangered western ground parrot / kyloring (Pezoporus flaviventris)

Pantoea stewartii, a plant pathogen, is primarily transmitted through contaminated seeds and insect vectors, with the corn flea beetle (Chaetocnema pulicaria) being the primary carrier. P. stewartii is a bacterium belonging to the order Enterobacterales and can lead to crop diseases that have a significant economic impact worldwide. Due to its high potential for spread, P. stewartii is classified as a quarantine organism in numerous countries. Despite its impact on agriculture, the limited genome sequences of P. stewartii hamper understanding of its pathogenicity and host specificity, and the development of effective control strategies. In this study, a P. stewartii strain (C10109_Jinnung) was discovered in the faecal matter of the Critically Endangered western ground parrot/kyloring (Pezoporus flaviventris) in Australia, which to our knowledge is the first reported P. stewartii genome from a bird source. Whole-genome sequencing and phylogenomic analysis of strain C10109_Jinnung, obtained from a captive psittacine, provides new insights into the genetic diversity and potential transmission route for the spread of P. stewartii beyond insects and plants, where P. stewartii is typically studied. Our findings provide new insights into the potential transmission route for spread of P. stewartii and expand the known transmission agents beyond insects and plants. Expanding the catalogue of P. stewartii genomes is fundamental to improving understanding of the pathogenicity, evolution and dissemination, and to develop effective control strategies to reduce the substantial economic losses associated with P. stewartii in various crops and the potential impact of endangered animal species

A varying kHz peak separation in 4U 1608-52

Using a new technique to improve the sensitivity to weak Quasi-Periodic Oscillations (QPO) we discovered a new QPO peak at about 1100 Hz in the March 1996 outburst observations of 4U 1608-52, simultaneous with the ~ 600-900 Hz peak previously reported from these data. The frequency separation between the upper and the lower QPO peak varied significantly from $232.7 \pm 11.5$ Hz on March 3, to $293.1 \pm 6.6$ Hz on March 6. This is the first case of a variable kHz peak separation in an atoll source.Comment: Aipproc LaTeX (4 pages, 2 ps-figures), to appear in "Accretion Processes in Astrophysical Systems", Proc. of the 8th Annual Astrophysics Conference in Maryland, S. S. Holt & T. Kallman (eds.

Subglacial lakes and hydrology across the Ellsworth Subglacial Highlands, West Antarctica

Subglacial water plays an important role in ice sheet dynamics and stability. Subglacial lakes are often located at the onset of ice streams and have been hypothesised to enhance ice flow downstream by lubricating the ice– bed interface. The most recent subglacial-lake inventory of Antarctica mapped nearly 400 lakes, of which ∼ 14 % are found in West Antarctica. Despite the potential importance of subglacial water for ice dynamics, there is a lack of detailed subglacial-water characterisation in West Antarctica. Using radio-echo sounding data, we analyse the ice–bed interface to detect subglacial lakes. We report 33 previously uncharted subglacial lakes and present a systematic analysis of their physical properties. This represents a ∼ 40 % increase in subglacial lakes in West Antarctica. Additionally, a new digital elevation model of basal topography of the Ellsworth Subglacial Highlands was built and used to create a hydropotential model to simulate the subglacial hydrological network. This allows us to characterise basal hydrology, determine subglacial water catchments and assess their connectivity. We show that the simulated subglacial hydrological catchments of the Rutford Ice Stream, Pine Island Glacier and Thwaites Glacier do not correspond to their ice surface catchments

Dust Devil Tracks

Dust devils that leave dark- or light-toned tracks are common on Mars and they can also be found on the Earth’s surface. Dust devil tracks (hereinafter DDTs) are ephemeral surface features with mostly sub-annual lifetimes. Regarding their size, DDT widths can range between ∼1 m and ∼1 km, depending on the diameter of dust devil that created the track, and DDT lengths range from a few tens of meters to several kilometers, limited by the duration and horizontal ground speed of dust devils. DDTs can be classified into three main types based on their morphology and albedo in contrast to their surroundings; all are found on both planets: (a) dark continuous DDTs, (b) dark cycloidal DDTs, and (c) bright DDTs. Dark continuous DDTs are the most common type on Mars. They are characterized by their relatively homogenous and continuous low albedo surface tracks. Based on terrestrial and martian in situ studies, these DDTs most likely form when surficial dust layers are removed to expose larger-grained substrate material (coarse sands of ≥500 μm in diameter). The exposure of larger-grained materials changes the photometric properties of the surface; hence leading to lower albedo tracks because grain size is photometrically inversely proportional to the surface reflectance. However, although not observed so far, compositional differences (i.e., color differences) might also lead to albedo contrasts when dust is removed to expose substrate materials with mineralogical differences. For dark continuous DDTs, albedo drop measurements are around 2.5 % in the wavelength range of 550–850 nm on Mars and around 0.5 % in the wavelength range from 300–1100 nm on Earth. The removal of an equivalent layer thickness around 1 μm is sufficient for the formation of visible dark continuous DDTs on Mars and Earth. The next type of DDTs, dark cycloidal DDTs, are characterized by their low albedo pattern of overlapping scallops. Terrestrial in situ studies imply that they are formed when sand-sized material that is eroded from the outer vortex area of a dust devil is redeposited in annular patterns in the central vortex region. This type of DDT can also be found in on Mars in orbital image data, and although in situ studies are lacking, terrestrial analog studies, laboratory work, and numerical modeling suggest they have the same formation mechanism as those on Earth. Finally, bright DDTs are characterized by their continuous track pattern and high albedo compared to their undisturbed surroundings. They are found on both planets, but to date they have only been analyzed in situ on Earth. Here, the destruction of aggregates of dust, silt and sand by dust devils leads to smooth surfaces in contrast to the undisturbed rough surfaces surrounding the track. The resulting change in photometric properties occurs because the smoother surfaces have a higher reflectance compared to the surrounding rough surface, leading to bright DDTs. On Mars, the destruction of surficial dust-aggregates may also lead to bright DDTs. However, higher reflective surfaces may be produced by other formation mechanisms, such as dust compaction by passing dust devils, as this may also cause changes in photometric properties. On Mars, DDTs in general are found at all elevations and on a global scale, except on the permanent polar caps. DDT maximum areal densities occur during spring and summer in both hemispheres produced by an increase in dust devil activity caused by maximum insolation. Regionally, dust devil densities vary spatially likely controlled by changes in dust cover thicknesses and substrate materials. This variability makes it difficult to infer dust devil activity from DDT frequencies. Furthermore, only a fraction of dust devils leave tracks. However, DDTs can be used as proxies for dust devil lifetimes and wind directions and speeds, and they can also be used to predict lander or rover solar panel clearing events. Overall, the high DDT frequency in many areas on Mars leads to drastic albedo changes that affect large-scale weather patterns