A New 3.25 Micron Absorption Feature toward Mon R2/IRS-3

A new 3.2--3.5~$\mu$m spectrum of the protostar Mon~R2/IRS-3 confirms our previous tentative detection of a new absorption feature near 3.25 $\mu$m. The feature in our new spectrum has a central wavelength of 3.256 $\mu$m (3071 cm$^{-1}$) and has a full-width at half maximum of 0.079 $\mu$m (75 cm$^{-1}$). We explore a possible identification with aromatic hydrocarbons at low temperatures, which absorb at a similar wavelength. If the feature is due to aromatics, the derived column density of C--H bonds is $\sim$1.8 $\times$ $10^{18}$ cm$^{-2}$. If the absorbing aromatic molecules are of roughly the same size as those responsible for aromatic emission features in the interstellar medium, then we estimate that $\sim$9\% of the cosmic abundance of carbon along this line of sight would be in aromatic hydrocarbons, in agreement with abundance estimates from emission features.Comment: 12 pages (26 kB), AASTex format. Also 1 Postscript figure (39 kB), tarred, compressed and uuencoded, added with 'figure' command. Postscript file or hardcopy available upon request to [email protected]. ApJL, in pres

Neutron time-of-flight measurements of charged-particle energy loss in inertial confinement fusion plasmas

Neutron spectra from secondary ^{3}H(d,n)α reactions produced by an implosion of a deuterium-gas capsule at the National Ignition Facility have been measured with order-of-magnitude improvements in statistics and resolution over past experiments. These new data and their sensitivity to the energy loss of fast tritons emitted from thermal ^{2}H(d,p)^{3}H reactions enable the first statistically significant investigation of charged-particle stopping via the emitted neutron spectrum. Radiation-hydrodynamic simulations, constrained to match a number of observables from the implosion, were used to predict the neutron spectra while employing two different energy loss models. This analysis represents the first test of stopping models under inertial confinement fusion conditions, covering plasma temperatures of k_{B}T≈1-4  keV and particle densities of n≈(12-2)×10^{24}  cm^{-3}. Under these conditions, we find significant deviations of our data from a theory employing classical collisions whereas the theory including quantum diffraction agrees with our data

Uncovering Dangerous Cheats: How Do Avian Hosts Recognize Adult Brood Parasites?

BACKGROUND: Co-evolutionary struggles between dangerous enemies (e.g., brood parasites) and their victims (hosts) lead to the emergence of sophisticated adaptations and counter-adaptations. Salient host tricks to reduce parasitism costs include, as front line defence, adult enemy discrimination. In contrast to the well studied egg stage, investigations addressing the specific cues for adult enemy recognition are rare. Previous studies have suggested barred underparts and yellow eyes may provide cues for the recognition of cuckoos Cuculus canorus by their hosts; however, no study to date has examined the role of the two cues simultaneously under a consistent experimental paradigm. METHODOLOGY/PRINCIPAL FINDINGS: We modify and extend previous work using a novel experimental approach--custom-made dummies with various combinations of hypothesized recognition cues. The salient recognition cue turned out to be the yellow eye. Barred underparts, the only trait examined previously, had a statistically significant but small effect on host aggression highlighting the importance of effect size vs. statistical significance. CONCLUSION: Relative importance of eye vs. underpart phenotypes may reflect ecological context of host-parasite interaction: yellow eyes are conspicuous from the typical direction of host arrival (from above), whereas barred underparts are poorly visible (being visually blocked by the upper part of the cuckoo's body). This visual constraint may reduce usefulness of barred underparts as a reliable recognition cue under a typical situation near host nests. We propose a novel hypothesis that recognition cues for enemy detection can vary in a context-dependent manner (e.g., depending on whether the enemy is approached from below or from above). Further we suggest a particular cue can trigger fear reactions (escape) in some hosts/populations whereas the same cue can trigger aggression (attack) in other hosts/populations depending on presence/absence of dangerous enemies that are phenotypically similar to brood parasites and costs and benefits associated with particular host responses

Comparative genomic analysis reveals evidence of two novel Vibrio species closely related to V. cholerae

Background: In recent years genome sequencing has been used to characterize new bacterial species, a method of analysis available as a result of improved methodology and reduced cost. Included in a constantly expanding list of Vibrio species are several that have been reclassified as novel members of the Vibrionaceae. The description of two putative new Vibrio species, Vibrio sp. RC341 and Vibrio sp. RC586 for which we propose the names V. metecus and V. parilis, respectively, previously characterized as non-toxigenic environmental variants of V. cholerae is presented in this study. Results: Based on results of whole-genome average nucleotide identity (ANI), average amino acid identity (AAI), rpoB similarity, MLSA, and phylogenetic analysis, the new species are concluded to be phylogenetically closely related to V. cholerae and V. mimicus. Vibrio sp. RC341 and Vibrio sp. RC586 demonstrate features characteristic of V. cholerae and V. mimicus, respectively, on differential and selective media, but their genomes show a 12 to 15% divergence (88 to 85% ANI and 92 to 91% AAI) compared to the sequences of V. cholerae and V. mimicus genomes (ANI <95% and AAI <96% indicative of separate species). Vibrio sp. RC341 and Vibrio sp. RC586 share 2104 ORFs (59%) and 2058 ORFs (56%) with the published core genome of V. cholerae and 2956 (82%) and 3048 ORFs (84%) with V. mimicus MB-451, respectively. The novel species share 2926 ORFs with each other (81% Vibrio sp. RC341 and 81% Vibrio sp. RC586). Virulence-associated factors and genomic islands of V. cholerae and V. mimicus, including VSP-I and II, were found in these environmental Vibrio spp. Conclusions: Results of this analysis demonstrate these two environmental vibrios, previously characterized as variant V. cholerae strains, are new species which have evolved from ancestral lineages of the V. cholerae and V. mimicus clade. The presence of conserved integration loci for genomic islands as well as evidence of horizontal gene transfer between these two new species, V. cholerae, and V. mimicus suggests genomic islands and virulence factors are transferred between these species.

Association Between an Increase in Serum Sodium and In-Hospital Mortality in Critically Ill Patients*

OBJECTIVES: In critically ill patients, dysnatremia is common, and in these patients, in-hospital mortality is higher. It remains unknown whether changes of serum sodium after ICU admission affect mortality, especially whether normalization of mild hyponatremia improves survival. DESIGN: Retrospective cohort study. SETTING: Ten Dutch ICUs between January 2011 and April 2017. PATIENTS: Adult patients were included if at least one serum sodium measurement within 24 hours of ICU admission and at least one serum sodium measurement 24-48 hours after ICU admission were available. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: A logistic regression model adjusted for age, sex, and Acute Physiology and Chronic Health Evaluation-IV-predicted mortality was used to assess the difference between mean of sodium measurements 24-48 hours after ICU admission and first serum sodium measurement at ICU admission (Δ48 hr-[Na]) and in-hospital mortality. In total, 36,660 patients were included for analysis. An increase in serum sodium was independently associated with a higher risk of in-hospital mortality in patients admitted with normonatremia (Δ48 hr-[Na] 5-10 mmol/L odds ratio: 1.61 [1.44-1.79], Δ48 hr-[Na] > 10 mmol/L odds ratio: 4.10 [3.20-5.24]) and hypernatremia (Δ48 hr-[Na] 5-10 mmol/L odds ratio: 1.47 [1.02-2.14], Δ48 hr-[Na] > 10 mmol/L odds ratio: 8.46 [3.31-21.64]). In patients admitted with mild hyponatremia and Δ48 hr-[Na] greater than 5 mmol/L, no significant difference in hospital mortality was found (odds ratio, 1.11 [0.99-1.25]). CONCLUSIONS: An increase in serum sodium in the first 48 hours of ICU admission was associated with higher in-hospital mortality in patients admitted with normonatremia and in patients admitted with hypernatremia

Measurement of the ttˉproductioncrosssectionint\bar{t} production cross section in p\bar{p}collisionsat collisions at \sqrt{s}$ = 1.8 TeV

We update the measurement of the top production cross section using the CDF detector at the Fermilab Tevatron. This measurement uses $t\bar{t}$ decays to the final states $e+\nu$+jets and $\mu+\nu$+jets. We search for $b$ quarks from $t$ decays via secondary-vertex identification or the identification of semileptonic decays of the $b$ and cascade $c$ quarks. The background to the $t\bar{t}$ production is determined primarily through a Monte Carlo simulation. However, we calibrate the simulation and evaluate its uncertainty using several independent data samples. For a top mass of 175 $GeV/c^2$, we measure $\sigma_{t\bar{t}}=5.1 \pm 1.5$ pb and $\sigma_{t\bar{t}}=9.2 \pm 4.3$ pb using the secondary vertex and the lepton tagging algorithms, respectively. Finally, we combine these results with those from other $t\bar{t}$ decay channels and obtain $\sigma_{t\bar{t}} = 6.5^{+1.7}_{-1.4}$ pb.Comment: The manuscript consists of 130 pages, 35 figures and 42 tables in RevTex. The manuscript is submitted to Physical Review D. Fixed typo in author lis

Search for Narrow Diphoton Resonances and for gamma-gamma+W/Z Signatures in p\bar p Collisions at sqrt(s)=1.8 TeV

We present results of searches for diphoton resonances produced both inclusively and also in association with a vector boson (W or Z) using 100 pb^{-1} of p\bar p collisions using the CDF detector. We set upper limits on the product of cross section times branching ratio for both p\bar p\to\gamma\gamma + X and p\bar p\to\gamma\gamma + W/Z. Comparing the inclusive production to the expectations from heavy sgoldstinos we derive limits on the supersymmetry-breaking scale sqrt{F} in the TeV range, depending on the sgoldstino mass and the choice of other parameters. Also, using a NLO prediction for the associated production of a Higgs boson with a W or Z boson, we set an upper limit on the branching ratio for H\to\gamma\gamma. Finally, we set a lower limit on the mass of a `bosophilic' Higgs boson (e.g. one which couples only to \gamma, W, and Z$ bosons with standard model couplings) of 82 GeV/c^2 at 95% confidence level.Comment: 30 pages, 11 figure

Search for the Supersymmetric Partner of the Top-Quark in ppˉp \bar{p} Collisions at s=1.8TeV\sqrt{s} = 1.8 {\rm TeV}

We report on a search for the supersymmetric partner of the top quark (stop) produced in $t \bar{t}$ events using $110 {\rm pb}^{-1}$ of $p \bar{p}$ collisions at $\sqrt{s} = 1.8 {\rm TeV}$ recorded with the Collider Detector at Fermilab. In the case of a light stop squark, the decay of the top quark into stop plus the lightest supersymmetric particle (LSP) could have a significant branching ratio. The observed events are consistent with Standard Model $t \bar{t}$ production and decay. Hence, we set limits on the branching ratio of the top quark decaying into stop plus LSP, excluding branching ratios above 45% for a LSP mass up to 40 {\rm GeV/c}$^{2}$.Comment: 11 pages, 4 figure

Measurement of the Strong Coupling Constant from Inclusive Jet Production at the Tevatron pˉp\bar pp Collider

We report a measurement of the strong coupling constant, $\alpha_s(M_Z)$, extracted from inclusive jet production in $p\bar{p}$ collisions at $\sqrt{s}=$1800 GeV. The QCD prediction for the evolution of $\alpha_s$ with jet transverse energy $E_T$ is tested over the range 40<$E_T$<450 GeV using $E_T$ for the renormalization scale. The data show good agreement with QCD in the region below 250 GeV. In the text we discuss the data-theory comparison in the region from 250 to 450 GeV. The value of $\alpha_s$ at the mass of the $Z^0$ boson averaged over the range 40<$E_T$<250 GeV is found to be $\alpha_s(M_{Z})= 0.1178 \pm 0.0001{(\rm stat)}^{+0.0081}_{-0.0095}{\rm (exp. syst)}$. The associated theoretical uncertainties are mainly due to the choice of renormalization scale (^{+6%}_{-4%}) and input parton distribution functions (5%).Comment: 7 pages, 3 figures, using RevTeX. Submitted to Physical Review Letter