The evolution of O2-producing cyanobacteria that use water as terminal reductant transformed Earth's atmosphere to one suitable for the evolution of aerobic metabolism and complex life. The ...innovation of water oxidation freed photosynthesis to invade new environments and visibly changed the face of the Earth. We offer a new hypothesis for how this process evolved, which identifies two critical roles for carbon dioxide in the Archean period. First, we present a thermodynamic analysis showing that bicarbonate (formed by dissolution of CO2) is a more efficient alternative substrate than water for O2 production by oxygenic phototrophs. This analysis clarifies the origin of the long debated "bicarbonate effect" on photosynthetic O2 production. We propose that bicarbonate was the thermodynamically preferred reductant before water in the evolution of oxygenic photosynthesis. Second, we have examined the speciation of manganese(II) and bicarbonate in water, and find that they form Mn-bicarbonate clusters as the major species under conditions that model the chemistry of the Archean sea. These clusters have been found to be highly efficient precursors for the assembly of the tetramanganese-oxide core of the water-oxidizing enzyme during biogenesis. We show that these clusters can be oxidized at electrochemical potentials that are accessible to anoxygenic phototrophs and thus the most likely building blocks for assembly of the first O2 evolving photoreaction center, most likely originating from green nonsulfur bacteria before the evolution of cyanobacteria.
In this paper we propose a distributed architecture to provide machine learning practitioners with a set of tools and cloud services that cover the whole machine learning development cycle: ranging ...from the models creation, training, validation and testing to the models serving as a service, sharing and publication. In such respect, the DEEP-Hybrid-DataCloud framework allows transparent access to existing e-Infrastructures, effectively exploiting distributed resources for the most compute-intensive tasks coming from the machine learning development cycle. Moreover, it provides scientists with a set of Cloud-oriented services to make their models publicly available, by adopting a serverless architecture and a DevOps approach, allowing an easy share, publish and deploy of the developed models.
Nanostructured near-IR antireflective layer was produced on a GaAs slab surface by direct femtosecond laser fabrication of a surface diffraction grating. The single nanostructured layer on the GaAs ...slab reduces its total reflection at the wavelength λ ≈ 2.5 μm by 42 %, in agreement with the second-order approximation of the effective medium theory, with negligible increase of its absorbance.
This final article about the CHOOZ experiment presents a complete description of the \(\bar{\nu}_e\) source and detector, the calibration methods and stability checks, the event reconstruction ...procedures and the Monte Carlo simulation. The data analysis, systematic effects and the methods used to reach our conclusions are fully discussed. Some new remarks are presented on the deduction of the confidence limits and on the correct treatment of systematic errors.
Initial results are presented from CHOOZ
1
The CHOOZ experiment is named after the new nuclear power station operated by Électricité de France (EdF) near the village of Chooz in the Ardennes region ...of France.
1
, a long-baseline reactor-neutrino vacuum-oscillation experiment. The data reported here were taken during the period March to October 1997, when the two reactors ran at combined power levels varying from zero to values approaching their full rated power of 8.5
GW
(thermal). Electron antineutrinos from the reactors were detected by a liquid scintillation calorimeter located at a distance of about 1
km
. The detector was constructed in a tunnel protected from cosmic rays by a 300
MWE
rock overburden. This massive shielding strongly reduced potentially troublesome backgrounds due to cosmic-ray muons, leading to a background rate of about one event per day, more than an order of magnitude smaller than the observed neutrino signal. From the statistical agreement between detected and expected neutrino event rates, we find (at 90% confidence level) no evidence for neutrino oscillations in the
ν
e
disappearance mode for the parameter region given approximately by
Δm
2>0.9
10
−3
eV
2
for maximum mixing and sin
22
θ>0.18 for large
Δm
2.
We present new results based on the entire CHOOZ (The CHOOZ experiment is named after the new nuclear power station operated by Électricité de France (EdF) near the village of Chooz in the Ardennes ...region of France) data sample. We find (at 90% confidence level) no evidence for neutrino oscillations in the
ν
̄
e
disappearance mode, for the parameter region given by approximately
δm
2>7·10
−4
eV
2
for maximum mixing, and sin
22
θ=0.10 for large
δm
2. Lower sensitivity results, based only on the comparison of the positron spectra from the two different-distance nuclear reactors, are also presented; these are independent of the absolute normalization of the
ν
̄
e
flux, the cross section, the number of target protons and the detector efficiencies.
Deep learning has been postulated as a solution for numerous problems in different branches of science. Given the resource-intensive nature of these models, they often need to be executed on ...specialized hardware such graphical processing units (GPUs) in a distributed manner. In the academic field, researchers get access to this kind of resources through High Performance Computing (HPC) clusters. This kind of infrastructures make the training of these models difficult due to their multi-user nature and limited user permission. In addition, different HPC clusters may possess different peculiarities that can entangle the research cycle (e.g., libraries dependencies). In this paper we develop a workflow and methodology for the distributed training of deep learning models in HPC clusters which provides researchers with a series of novel advantages. It relies on udocker as containerization tool and on Horovod as library for the distribution of the models across multiple GPUs. udocker does not need any special permission, allowing researchers to run the entire workflow without relying on any administrator. Horovod ensures the efficient distribution of the training independently of the deep learning framework used. Additionally, due to containerization and specific features of the workflow, it provides researchers with a cluster-agnostic way of running their models. The experiments carried out show that the workflow offers good scalability in the distributed training of the models and that it easily adapts to different clusters.
We report on our experience of repair of congenital duodenal obstruction using a circumumbilical incision. The aim of this report is to describe how a Bianchi approach provides a safe and invisible ...alternative to transverse abdominal incision for the repair of duodenal atresia.
Between January 2005 and December 2009, we treated 13 cases with congenital duodenal obstruction using a circumumbilical incision (Group I) and 14 cases with this condition repaired using a standard transverse right upper abdominal incision (Group II). Surgical procedures included a diamond-shaped duodenoduodenostomy as originally described by Kimura and standard duodenal web excision. The circumumbilical incision utilized at our institution is a classic Bianchi procedure. The 2 groups were compared with regard to patient demographics, operative reports and postoperative outcomes.
There were no differences in preoperative parameters such as gestational age, age at surgery, or body weight at operation between the 2 groups. The circumumbilical cohort and transverse incision cohort had similar rates of congenital anomalies (61.54% vs. 64.29%), Kimura diamond-shaped anastomosis (61.54% vs. 64.29%) with only a slight female predominance in Group I. The mean operating time in Group I was 65.0 min while mean duration of the operation in Group II was 64.64 min. The difference between groups was statistically not significant (p>0.05). The mean time to full enteral feeding for patients with an umbilical incision was significantly shorter (p<0.0001) compared to patients with a standard incision (6.92 days vs. 11.86 days). Mean postoperative hospital stay was longer for patients in Group II (19.71 days vs. 12.38 days; p<0.0001). The postoperative course was uneventful for all patients. There were no intra- or postoperative complications.
We report on a first series comparing umbilical and transverse right upper abdominal incision for the treatment of congenital duodenal obstruction. Our results suggest that an umbilical incision offers all the benefits of a minimal access approach, including earlier feeding and shorter times to discharge. We consider our approach an intermediate step, with laparoscopy likely to become the "gold standard" for the treatment of congenital duodenal obstruction.
PDF
