The uptake of carbonyl sulfide (COS) by terrestrial plants is linked to
photosynthetic uptake of CO2 as these gases partly share the same
uptake pathway. Applying COS as a photosynthesis tracer in ...models requires an
accurate representation of biosphere COS fluxes, but these models have not
been extensively evaluated against field observations of COS fluxes. In this
paper, the COS flux as simulated by the Simple Biosphere Model, version 4
(SiB4), is updated with the latest mechanistic insights and evaluated with site
observations from different biomes: one evergreen needleleaf forest, two
deciduous broadleaf forests, three grasslands, and two crop fields spread over
Europe and North America. We improved SiB4 in several ways to improve its
representation of COS. To account for the effect of atmospheric COS mole
fractions on COS biosphere uptake, we replaced the fixed atmospheric COS mole
fraction boundary condition originally used in SiB4 with spatially and
temporally varying COS mole fraction fields. Seasonal amplitudes of COS mole
fractions are ∼50–200 ppt at the investigated sites with a
minimum mole fraction in the late growing season. Incorporating seasonal
variability into the model reduces COS uptake rates in the late growing
season, allowing better agreement with observations. We also replaced the
empirical soil COS uptake model in SiB4 with a mechanistic model that
represents both uptake and production of COS in soils, which improves the
match with observations over agricultural fields and fertilized grassland
soils. The improved version of SiB4 was capable of simulating the diurnal and
seasonal variation in COS fluxes in the boreal, temperate, and Mediterranean
region. Nonetheless, the daytime vegetation COS flux is underestimated on
average by 8±27 %, albeit with large variability across sites. On a
global scale, our model modifications decreased the modeled COS terrestrial
biosphere sink from 922 Gg S yr−1 in the original SiB4 to
753 Gg S yr−1 in the updated version. The largest decrease in
fluxes was driven by lower atmospheric COS mole fractions over regions with
high productivity, which highlights the importance of accounting for
variations in atmospheric COS mole fractions. The change to a different soil
model, on the other hand, had a relatively small effect on the global
biosphere COS sink. The secondary role of the modeled soil component in the
global COS budget supports the use of COS as a global photosynthesis tracer. A
more accurate representation of COS uptake in SiB4 should allow for improved
application of atmospheric COS as a tracer of local- to global-scale
terrestrial photosynthesis.
A search for high-energy neutrinos interacting within the IceCube detector between 2010 and 2012 provided the first evidence for a high-energy neutrino flux of extraterrestrial origin. Results from ...an analysis using the same methods with a third year (2012-2013) of data from the complete IceCube detector are consistent with the previously reported astrophysical flux in the 100 TeV-PeV range at the level of 10(-8) GeV cm-2 s-1 sr-1 per flavor and reject a purely atmospheric explanation for the combined three-year data at 5.7σ. The data are consistent with expectations for equal fluxes of all three neutrino flavors and with isotropic arrival directions, suggesting either numerous or spatially extended sources. The three-year data set, with a live time of 988 days, contains a total of 37 neutrino candidate events with deposited energies ranging from 30 to 2000 TeV. The 2000-TeV event is the highest-energy neutrino interaction ever observed.
The results of a 3 + 1 sterile neutrino search using eight years of data from the IceCube Neutrino Observatory are presented. A total of 305 735 muon neutrino events are analyzed in reconstructed ...energy-zenith space to test for signatures of a matter-enhanced oscillation that would occur given a sterile neutrino state with a mass-squared differences between 0.01 and 100 eV2. The best-fit point is found to be at sin2(2θ24) = 0.10 and Δm412 = 4.5 eV2, which is consistent with the no sterile neutrino hypothesis with a p value of 8.0%.
We present a search for a light sterile neutrino using three years of atmospheric neutrino data from the DeepCore detector in the energy range of approximately 10–60 GeV. DeepCore is the low-energy ...subarray of the IceCube Neutrino Observatory. The standard three-neutrino paradigm can be probed by adding an additional light (Δm412∼1 eV2) sterile neutrino. Sterile neutrinos do not interact through the standard weak interaction and, therefore, cannot be directly detected. However, their mixing with the three active neutrino states leaves an imprint on the standard atmospheric neutrino oscillations for energies below 100 GeV. A search for such mixing via muon neutrino disappearance is presented here. The data are found to be consistent with the standard three-neutrino hypothesis. Therefore, we derive limits on the mixing matrix elements at the level of |Uμ4|2<0.11 and |Uτ4|2<0.15 (90% C.L.) for the sterile neutrino mass splitting Δm412=1.0 eV2.
This study examines the effects of puberty and sex on the intrinsic functional connectivity (iFC) of brain networks, with a focus on the default-mode network (DMN). Consistently implicated in ...depressive disorders, the DMN's function may interact with puberty and sex in the development of these disorders, whose onsets peak in adolescence, and which show strong sex disproportionality (females > males). The main question concerns how the DMN evolves with puberty as a function of sex. These effects are expected to involve within- and between-network iFC, particularly, the salience and the central-executive networks, consistent with the Triple-Network Model. Resting-state scans of an adolescent community sample (n = 304, male/female: 157/147; mean/std age: 14.6/0.41 years), from the IMAGEN database, were analyzed using the AFNI software suite and a data reduction strategy for the effects of puberty and sex. Three midline regions (medial prefrontal, pregenual anterior cingulate, and posterior cingulate), within the DMN and consistently implicated in mood disorders, were selected as seeds. Within- and between-network clusters of the DMN iFC changed with pubertal maturation differently in boys and girls (puberty-X-sex). Specifically, pubertal maturation predicted weaker iFC in girls and stronger iFC in boys. Finally, iFC was stronger in boys than girls independently of puberty. Brain-behavior associations indicated that lower connectivity of the anterior cingulate seed predicted higher internalizing symptoms at 2-year follow-up. In conclusion, weaker iFC of the anterior DMN may signal disconnections among circuits supporting mood regulation, conferring risk for internalizing disorders.
A diffuse flux of astrophysical neutrinos above 100 TeV has been observed at the IceCube Neutrino Observatory. Here we extend this analysis to probe the astrophysical flux down to 35 TeV and analyze ...its flavor composition by classifying events as showers or tracks. Taking advantage of lower atmospheric backgrounds for showerlike events, we obtain a shower-biased sample containing 129 showers and 8 tracks collected in three years from 2010 to 2013. We demonstrate consistency with the (fe:fμ:fτ)⊕≈(1:1:1)⊕ flavor ratio at Earth commonly expected from the averaged oscillations of neutrinos produced by pion decay in distant astrophysical sources. Limits are placed on nonstandard flavor compositions that cannot be produced by averaged neutrino oscillations but could arise in exotic physics scenarios. A maximally tracklike composition of (0:1:0)⊕ is excluded at 3.3σ, and a purely showerlike composition of (1:0:0)⊕ is excluded at 2.3σ.
The IceCube Neutrino Observatory has observed a diffuse flux of TeV-PeV astrophysical neutrinos at 5.7sigma significance from an all-flavor search. The direct detection of tau neutrinos in this flux ...has yet to occur. Tau neutrinos become distinguishable from other flavors in IceCube at energies above a few hundred TeV, when the cascade from the tau neutrino charged current interaction becomes resolvable from the cascade from the tau lepton decay. This paper presents results from the first dedicated search for tau neutrinos with energies between 214 TeV and 72 PeV in the full IceCube detector. The analysis searches for IceCube optical sensors that observe two separate pulses in a single event-one from the tau neutrino interaction and a second from the tau decay. No candidate events were observed in three years of IceCube data. For the first time, a differential upper limit on astrophysical tau neutrinos is derived around the PeV energy region, which is nearly 3 orders of magnitude lower in energy than previous limits from dedicated tau neutrino searches.
Internationally, guidelines to prevent secondary transmission of Shigella infection vary widely. Cases, their contacts with diarrhoea, and those in certain occupational groups are frequently excluded ...from work, school, or daycare. In the Netherlands, all contacts attending pre-school (age 0-3) and junior classes in primary school (age 4-5), irrespective of symptoms, are also excluded pending microbiological clearance. We identified risk factors for secondary Shigella infection (SSI) within households and evaluated infection control policy in this regard.
This retrospective cohort study of households where a laboratory confirmed Shigella case was reported in Amsterdam (2002-2009) included all households at high risk for SSI (i.e. any household member under 16 years). Cases were classified as primary, co-primary or SSIs. Using univariable and multivariable binomial regression with clustered robust standard errors to account for household clustering, we examined case and contact factors (Shigella serotype, ethnicity, age, sex, household size, symptoms) associated with SSI in contacts within households.
SSI occurred in 25/ 337 contacts (7.4%): 20% were asymptomatic, 68% were female, and median age was 14 years (IQR: 4-38). In a multivariable model adjusted for case and household factors, only diarrhoea in contacts was associated with SSI (IRR 8.0, 95% CI:2.7-23.8). In a second model, factors predictive of SSI in contacts were the age of case (0-3 years (IRRcase≥6 years:2.5, 95% CI:1.1-5.5) and 4-5 years (IRRcase≥6 years:2.2, 95% CI:1.1-4.3)) and household size (>6 persons (IRR2-4 persons 3.4, 95% CI:1.2-9.5)).
To identify symptomatic and asymptomatic SSI, faecal screening should be targeted at all household contacts of preschool cases (0-3 years) and cases attending junior class in primary school (4-5 years) and any household contact with diarrhoea. If screening was limited to these groups, only one asymptomatic adult carrier would have been missed, and potential exclusion of 70 asymptomatic contacts <6 years old from school or daycare, who were contacts of cases of all ages, could have been avoided.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The surface detector array of the Pierre Auger Observatory provides information about the longitudinal development of the muonic component of extensive air showers. Using the timing information from ...the flash analog-to-digital converter traces of surface detectors far from the shower core, it is possible to reconstruct a muon production depth distribution. We characterize the goodness of this reconstruction for zenith angles around 60degrees and different energies of the primary particle. From these distributions, we define X super( mu ) sub(max) as the depth along the shower axis where the production of muons reaches maximum. We explore the potentiality of X super( mu ) sub(max) as a useful observable to infer the mass composition of ultrahigh-energy cosmic rays. Likewise, we assess its ability to constrain hadronic interaction models.
PDF
