A Deep Probe of the Galaxy Stellar Mass Functions at z~1-3 with the GOODS NICMOS Survey

We use a sample of 8298 galaxies observed in the HST GOODS NICMOS Survey (GNS) to construct the galaxy stellar mass function as a function of both redshift and stellar mass up to z=3.5 and down to masses of Mstar=10^8.5 Msun at z~1. We discover that a significant fraction of all massive Mstar>10^11 Msun galaxies are in place up to the highest redshifts we probe, with a decreasing fraction of lower mass galaxies present at all redshifts. This is an example of `galaxy mass downsizing', and is the result of massive galaxies forming before lower mass ones, and not just simply ending their star formation earlier as in traditional downsizing scenarios. We find that the faint end slope is significantly steeper than what is found in previous investigations. We demonstrate that this steeper mass function better matches the stellar mass added due to star formation, thereby alleviating some of the mismatch between these two measures of the evolution of galaxy mass. We furthermore examine the stellar mass function divided into blue/red systems, as well as for star forming and non-star forming galaxies. We find a similar mass downsizing present for both blue/red and star-forming/non-star forming galaxies, and that the low mass galaxies are mostly all blue, and are therefore creating the steep mass functions. We furthermore show that, although there is a downsizing such that high mass galaxies are nearer their z=0 values at high redshift, this turns over at masses Mstar~10^10 Msun, such that the lowest mass galaxies are more common than galaxies at slight higher masses, creating a `dip' in the observed galaxy mass function. We argue that the galaxy assembly process may be driven by different mechanisms at low and high masses, and that the efficiency of the galaxy formation process is lowest at masses Mstar~10^10 Msun at 1<z<3. (Abridged)Comment: 16 pages, 11 figures, MNRAS, accepte

Advancements in the fabrication and characterization of actinide targets for superheavy element production

The heaviest elements can exclusively be produced in actinide-target based nuclear fusion reactions with intense heavy-ion beams. Ever more powerful accelerators deliver beams of continuously increasing intensity, which brings targets of current technology to their limits and beyond. We motivate efforts to produce targets with improved properties, which calls for a better understanding of targets produced by molecular plating, the current standard method. Complementary analytical methods will help shedding more light on their chemical and physical changes in the beam. Special emphasis is devoted to the aspect of the optimum target thickness and the choice of the backing material

Citizens AND HYdrology (CANDHY): conceptualizing a transdisciplinary framework for citizen science addressing hydrological challenges

Widely available digital technologies are empowering citizens who are increasingly well informed and involved in numerous water, climate, and environmental challenges. Citizen science can serve many different purposes, from the "pleasure of doing science" to complementing observations, increasing scientific literacy, and supporting collaborative behaviour to solve specific water management problems. Still, procedures on how to incorporate citizens' knowledge effectively to inform policy and decision-making are lagging behind. Moreover, general conceptual frameworks are unavailable, preventing the widespread uptake of citizen science approaches for more participatory cross-sectorial water governance. In this work, we identify the shared constituents, interfaces, and interlinkages between hydrological sciences and other academic and non-academic disciplines in addressing water issues. Our goal is to conceptualize a transdisciplinary framework for valuing citizen science and advancing the hydrological sciences. Joint efforts between hydrological, computer, and social sciences are envisaged for integrating human sensing and behavioural mechanisms into the framework. Expanding opportunities of online communities complement the fundamental value of on-site surveying and indigenous knowledge. This work is promoted by the Citizens AND HYdrology (CANDHY) Working Group established by the International Association of Hydrological Sciences (IAHS)

Prevalence of eimeira spp. Oocysts in dairy properties in pelotas region in Rio Grande Do Sul, Brazil / Prevalência de oocistos de eimeira spp. Em propriedades leiteiras da região de pelotas no Rio Grande Do Sul, Brasil

The South of Brazil has been occupying the first place in the ranking of milk production in the country and Rio Grande do Sul annually produces a total of 4.5 billion liters, positioning itself as the fifth largest producer in the country. These numbers could be better, were it not for the economic losses due to mortality, low productive performance and expenses, due to diseases such as coccidiosis. Eimeria penetrates the intestinal cells, multiplies, causing local lesions that impair digestive processes reducing the absorption of nutrients. The work aimed to carry out an epidemiological, retrospective survey of the prevalence of oocysts of Eimeria spp. on small dairy farms located in Pelotas region of RS. The results were obtained in the database of diagnoses performed in the laboratory of the Study Group on Parasitic Diseases (GEEP), at the Federal University of Pelotas (UFPel). Results from 505 stool samples were used. Fecal samples were analyzed using the Gordon and Whitlock technique (1939) and the result expressed in oocysts per gram of feces. Of the analyzed samples, 54.65% (276/505) were positive for oocysts of this genus, with an average count of 545 oocysts per gram of feces. It is concluded that this protozoan has a high prevalence in dairy farms located in the Southern region of RS.

The Characteristic Star Formation Histories of Galaxies at Redshifts z~2-7

A large sample of spectroscopically confirmed galaxies at 1.4<z<3.7, with complementary imaging in the near- and mid-IR from the ground and from Hubble and Spitzer, is used to infer the average star formation histories (SFHs) of typical galaxies from z~7 to 2. For a subset of 302 galaxies at 1.5<z<2.6, we perform a comparison of star formation rates (SFRs) determined from SED modeling (SFRs[SED]) and those calculated from deep Keck UV and Spitzer/MIPS 24 micron imaging (SFRs[IR+UV]). Exponentially declining SFHs yield SFRs[SED] that are 5-10x lower on average than SFRs[IR+UV], indicating that declining SFHs may not be accurate for typical galaxies at z>2. The SFRs of z~2-3 galaxies are directly proportional to their stellar masses M*, with unity slope---a result that is confirmed with Spitzer/IRAC stacks of 1179 UV-faint (R>25.5) galaxies---for M*>5e8 Msun and SFRs >2 Msun/yr. We interpret this result in the context of several systematic biases that can affect determinations of the SFR-M* relation. The average specific SFRs at z~2-3 are similar within a factor of two to those measured at z>4, implying an average SFH where SFRs increase with time. A consequence of these rising SFHs is that (a) a substantial fraction of UV-bright z~2-3 galaxies had faint sub-L* progenitors at z>4; and (b) gas masses must increase with time from z=7 to 2, over which time the net cold gas accretion rate---as inferred from the specific SFR and the Kennicutt-Schmidt relation---is ~2-3x larger than the SFR . However, if we evolve to higher redshift the SFHs and masses of the halos that are expected to host L* galaxies at z~2, we find that <10% of the baryons accreted onto typical halos at z>4 actually contribute to star formation at those epochs. These results highlight the relative inefficiency of star formation even at early cosmic times when galaxies were first assembling. [Abridged]Comment: 34 pages, 29 figures, 8 tables, accepted for publication in Ap

Evolution of Massive Galaxy Structural Properties and Sizes via Star Formation In the GOODS NICMOS Survey

We present a study of the resolved star-forming properties of a sample of distant massive M_*>10^11M_solar galaxies in the GOODS NICMOS Survey (GNS). We derive dust corrected UV star formation rates (SFRs) as a function of radius for 45 massive galaxies within the redshift range 1.5<z<3 in order to measure the spatial location of ongoing star formation. We find that the star formation rates present in different regions of a galaxy reflect the already existent stellar mass density, i.e. high density regions have higher star formation rates than lower density regions, on average. This observed star formation is extrapolated in several ways to the present day, and we measure the amount of new stellar mass that is created in individual portions of each galaxy to determine how the stellar mass added via star formation changes the observed stellar mass profile, the Sersic index (n) and effective radius (R_e) over time. We find that these massive galaxies fall into three broad classifications of star formation distribution. These different star formation distributions increase the effective radii over time, which are on average a factor of ~16pm5% larger, with little change in n (average Delta n=-0.9pm0.9) after evolution. We also implement a range of simple stellar migration models into the simulated evolutionary path of these galaxies in order to gauge its effect on the properties of our sample. This yields a larger increase in the evolved R_e than the pure static star formation model, with a maximum average increase of Delta R_e~54pm19%, but with little change in n, Delta n ~-1.1pm1.3. These results are not in agreement with the observed change in the R_e and n between z~2.5 and 0 obtained via various observational studies. We conclude that star formation and stellar migration alone cannot account for the observed change in structural parameters for this galaxy population (abridged).Comment: Accepted by MNRAS 18 pages 8 figure

Reaction of Neptunium with Molecular and Atomic Oxygen: Formation and Stability of Surface Oxides

The surface reactions of thin films of Np metal with molecular and atomic oxygen were investigated by Xray and Ultra-Violet Photoelectron Spectroscopy (XPS and UPS, respectively). Goal of this work was to study the entire range of oxides, starting with the very early reaction stages, in presence of metal, up to the highest possible oxides, reached at saturation under highly reactive, oxidative conditions. Emphasis was given to the surface layers, whose properties often differ from the bulk, and which are directly involved in corrosion processes of solids. Molecular O2 reacts readily with the metallic neptunium surface to form the sesquioxide and dioxide. The sesquioxide is observed as thin ¿bulk¿ species of up to nine monolayers thickness. A higher oxide, identified as Np2O5, is formed when the NpO2 surface is exposed to atomic oxygen. It is stable under UHV conditions up to a temperature of about 200 C. The high oxide, Np2O5, is still capable of chemisorbing further oxygen. This is shown in UPS spectra by the additional O-2p line at 5¿6 eV BE, superimposing onto the valence band (VB). The formation of both a lower (Np2O3) and higher oxide (Np2O5) besides the dioxide is discussed in the framework of ongoing 5f localization throughout the actinide series.JRC.E.6-Actinides researc

Redoc Reactions of Plutonium with Hydroquinone and Humic Substances

see attachmentJRC.E.6-Actinides researc

Interaction of PuO2 Thin Films with Water

see attachmentJRC.DG.E.6-Actinides researc

Search for Higher Oxides of Pu - Photoemission Study

After decades of believing in a very stable PuO2, suitable for final storage of nuclear waste, the existence of a higher oxide, PuO2+x, was recently claimed. This would have far reaching consequences on the strategies of storage of Pu-based waste. Its formation therefore has been discussed controversially for several years. In this work, existence and stability of the higher oxide, PuO2+x, has been probed by photoelectron spectroscopy study of PuO2 exposed to atomic oxygen. The validity of this approach is first tested on UO2, which oxidizes readily to UO3. Under the same reaction conditions, PuO2 is only covered by a chemisorbed layer of oxygen, which desorbs at elevated temperature. The study excludes the stability of any higher binary Pu oxide as a bulk species.JRC.E.6-Actinides researc