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The Changing Scientific and Technological Basis of the CBW Proliferation Problem
Ye
The Brown Dwarf Kinematics Project (BDKP). II. Details on Nine Wide Common Proper Motion Very Low-Mass Companions to Nearby Stars
We report on nine wide common proper motion systems containing late-type M,
L, or T companions. We confirm six previously reported companions, and identify
three new systems. The ages of these systems are determined using diagnostics
for both stellar primaries and low--mass secondaries and masses for the
secondaries are inferred using evolutionary models. Of our three new
discoveries, the M3+T6.5 pair G 204-39 and SDSS J1758+4633 has an age
constrained to 0.5-1.5 Gyr making the secondary a potentially useful brown
dwarf benchmark. The G5+L4 pair G 200-28 and SDSS J1416+5006 has a projected
separation of ~25,000 AU making it one of the widest and lowest binding energy
systems known to date. The system containing NLTT 2274 and SDSS J0041+1341 is
an older M4+L0 (>4.5 Gyr) pair which shows Halpha activity in the secondary but
not the primary making it a useful tracer of age/mass/activity trends. We find
a resolved binary frequency for widely-separated (> 100 AU) low--mass
companions (i.e. at least a triple system) which is at least twice the
frequency found for the field ultracool dwarf population. The ratio of triples
to binaries and quadruples to binaries is also high for this sample: 3:5 and
1:4, respectively, compared to 8-parsec sample values of 1:4 and 1:26. The
additional components in these wide companion systems indicates a formation
mechanism that requires a third or fourth component to maintain gravitational
stability or facilitate the exchange of angular momentum. The binding energies
for the nine multiples discussed in this text are among the lowest known for
wide low-mass systems, suggesting that weakly bound, low--to--intermediate mass
(0.2M_sun < M_tot <1.0M_sun) multiples can form and survive to exist in the
field (1-8 Gyr).Comment: 62 pages, 12 figures, 11 Tables, AJ accepted for publicatio
Interferon lambda protects the female reproductive tract against Zika virus infection
Zika virus infections can cause devastating congenital birth defects but the underlying interactions with the host immune system are not well understood. Here, the authors examine the immune basis of vaginal protection and susceptibility to Zika viral infection, and identify a hormonal dependent role for interferon-lambda-mediated protection against disease
Maternal high-fat diet induces hyperproliferation and alters Pten/Akt signaling in prostates of offspring
Developing recommendations for prostate cancer prevention requires identification of modifiable risk factors. Maternal exposure to high-fat diet (HFD) initiates a broad array of second-generation adult disorders in murine models and humans. Here, we investigate whether maternal HFD in mice affects incidence of prostate hyperplasia in offspring. Using three independent assays, we demonstrate that maternal HFD is sufficient to initiate prostate hyperproliferation in adult male offspring. HFD-exposed prostate tissues do not increase in size, but instead concomitantly up-regulate apoptosis. Maternal HFD-induced phenotypes are focally present in young adult subjects and greatly exacerbated in aged subjects. HFD-exposed prostate tissues additionally exhibit increased levels of activated Akt and deactivated Pten. Taken together, we conclude that maternal HFD diet is a candidate modifiable risk factor for prostate cancer initiation in later life
Caffeinated Alcoholic Beverages â An Emerging Trend in Alcohol Abuse
Alcohol use disorders are pervasive in society and their impact affects quality of life, morbidity and mortality, as well as individual productivity. Alcohol has detrimental effects on an individualâs physiology and nervous system, and is associated with disorders of many organ and endocrine systems impacting an individualâs health, behavior, and ability to interact with others. Youth are particularly affected. Unfortunately, adolescent usage also increases the probability for a progression to dependence. Several areas of research indicate that the deleterious effects of alcohol abuse may be exacerbated by mixing caffeine with alcohol. Some behavioral evidence suggests that caffeine increases alcohol drinking and binge drinking episodes, which in turn can foster the development of alcohol dependence. As a relatively new public health concern, the epidemiological focus has been to establish a need for investigating the effects of caffeinated alcohol. While the trend of co-consuming these substances is growing, knowledge of the central mechanisms associated with caffeinated ethanol has been lacking. Research suggests that caffeine and ethanol can have additive or synergistic pharmacological actions and neuroadaptations, with the adenosine and dopamine systems in particular implicated. However, the limited literature on the central effects of caffeinated ethanol provides an impetus to increase our knowledge of the neuroadaptive effects of this combination and their impact on cognition and behavior. Research from our laboratories indicates that an established rodent animal model of alcoholism can be extended to investigate the acute and chronic effects of caffeinated ethanol
The Brown Dwarf Kinematics Project (BDKP). III. Parallaxes for 70 Ultracool Dwarfs
We report parallax measurements for 70 ultracool dwarfs (UCDs). Using both
literature values and our sample, we report new polynomial relations between
spectral type and M. Including resolved L/T transition binaries in the
relations, we find no reason to differentiate between a "bright" (unresolved
binary) and "faint" (single source) sample across the L/T boundary. Isolating
early T dwarfs, we find that the brightening of T0-T4 sources is prominent in
M where there is a [1.2 - 1.4] magnitude difference. A similar yet
dampened brightening of [0.3 - 0.5] magnitude happens at M and a plateau
or dimming of [-0.2 - -0.3] magnitude is seen in M. Comparing with
evolutionary models that vary gravity, metallicity, and cloud thickness we find
that a near constant temperature of 1200 100 K along a narrow spectral
subtype of T0-T4 is required to account for the brightening and color magnitude
diagram of the L-dwarf/T-dwarf transition. Furthermore, there is a significant
population of both L and T dwarfs which are red or potentially "ultra-cloudy"
compared to the models, many of which are known to be young indicating a
correlation between enhanced photospheric dust and youth. For the low
surface-gravity or young companion L dwarfs we find that 8 out of 10 are at
least [0.2-1.0] magnitude underluminous in M and/or M compared to
equivalent spectral type objects. We speculate that this is a consequence of
increased dust opacity and conclude that low-surface gravity L dwarfs require a
completely new spectral-type/absolute magnitude polynomial for analysis.Comment: 65 pages, Accepted for publication to Ap
Transferring an Outcome-Oriented Learning Architecture to an IT Learning Game
Schmitz, B., Klemke, R., Totschnig, M., Czauderna, A., & Specht, M. (2011). Transferring an Outcome-Oriented Learning Architecture to an IT Learning Game. In C. D. Kloos, D. Gillet, R. M. Crespo CarcĂa, F. Wild, & M. Wolpers (Eds.), Towards Ubiquitous Learning: 6th European Conference on Technology Anhanced Learning, EC-TEL 2011 (pp. 483-488). September, 20-23, 2011, Palermo, Italy. LNCS 6964; Heidelberg, Berlin: Springer.Todayâs technology enhanced learning scenarios focus on outcome-oriented delivery of learning processes, contents, and services. Also, learners increasingly demand for innovative and motivating learning scenarios that match their habits of using media. The European project ICOPER researches outcome-oriented learning infrastructures for higher education contexts. The German BMBF-project SpITKom aims at transferring such approaches to basic qualification. Based on a Browser Game, it uses ICOPERâs technical infrastructure which combines learning object metadata repositories, learning outcome repositories, learning design repositories and learner profile repositories. This paper initially depicts the technical infrastructure of an outcome-oriented learning scenario that was developed in the course of ICOPER and then outlines its transformation to the game-based learning approach as realized in the course of SpITKom.ICOPER, SPITKO
Hubble Space Telescope NICMOS Observations of T Dwarfs: Brown Dwarf Multiplicity and New Probes of the L/T Transition
We present the results of a Hubble Space Telescope NICMOS imaging survey of
22 T-type field brown dwarfs. Five are resolved as binary systems with angular
separations of 0"05-0"35, and companionship is established on the basis of
component F110W-F170M colors (indicative of CH4 absorption) and low
probabilities of background contamination. Prior ground-based observations show
2MASS 1553+1532AB to be a common proper motion binary. The properties of these
systems - low multiplicity fraction (11[+7][-3]% resolved, as corrected for
sample selection baises), close projected separations (a = 1.8-5.0 AU) and
near-unity mass ratios - are consistent with previous results for field brown
dwarf binaries. Three of the binaries have components that span the
poorly-understood transition between L dwarfs and T dwarfs. Spectral
decomposition analysis of one of these, SDSS 1021-0304AB, reveals a peculiar
flux reversal between its components, as its T5 secondary is ~30% brighter at
1.05 and 1.27 micron than its T1 primary. This system, 2MASS 0518-2828AB and
SDSS 1534+1615AB all demonstrate that the J-band brightening observed between
late-type L to mid-type T dwarfs is an intrinsic feature of this spectral
transition, albeit less pronounced than previously surmised. We also find that
the resolved binary fraction of L7 to T3.5 dwarfs is twice that of other L and
T dwarfs, an anomaly that can be explained by a relatively rapid evolution of
brown dwarfs through the L/T transition, perhaps driven by dynamic
(nonequilibrium) depletion of photospheric condensates.Comment: ~40 pages, 17 figures, accepted for publication to ApJ. Note that
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