43 research outputs found
Learning to assemble objects with a robot swarm
Large populations of simple robots can solve complex tasks, but controlling them is still a challenging problem, due to limited communication and computation power. In order to assemble objects, have shown that a human controller can solve such a task. Instead, we investigate how to learn the assembly of multiple objects with a single central controller. We propose splitting the assembly process in two sub-tasks -- generating a top-level assembly policy and learning an object movement policy. The assembly policy plans the trajectories for each object and the object movement policy controls the trajectory execution.The resulting system is able to solve assembly tasks with varying object shapes being assembled as shown in multiple simulation scenarios
Impact of estrogen receptor alpha on the tamoxifen resistance in breast cancer patients
Genetic aberrations and changes in the activity of estrogen receptors alpha (ERa[lpha]) play an important role in the endocrine sensitivity. The aim of this study was to examine the relationship between the ESR1 expression level, its polymorphic variants, and the distribution pattern of ER[alpha] expression with the prognosis and efficacy of tamoxifen treatment in breast cancer patients. Our data suggest that the ESR1 expression level, SNPs in the ESR1 gene and the distribution pattern of ERα expression can be a potential molecular marker of tamoxifen resistance in breast cancer patients
DNA Barcoding for Community Ecology - How to Tackle a Hyperdiverse, Mostly Undescribed Melanesian Fauna
Trigonopterus weevils are widely distributed throughout Melanesia and hyperdiverse in New Guinea. They are a dominant feature in natural forests, with narrow altitudinal zonation. Their use in community ecology has been precluded by the "taxonomic impediment".
We sampled >6,500 specimens from seven areas across New Guinea; 1,002 specimens assigned to 270 morphospecies were DNA sequenced. Objective clustering of a refined dataset (excluding nine cryptic species) at 3% threshold revealed 324 genetic clusters (DNA group count relative to number of morphospecies = 20.0% overestimation of species diversity, or 120.0% agreement) and 85.6% taxonomic accuracy (the proportion of DNA groups that "perfectly" agree with morphology-based species hypotheses). Agreement and accuracy were best at an 8% threshold. GMYC analysis revealed 328 entities (21.5% overestimation) with 227 perfect GMYC entities (84.1% taxonomic accuracy). Both methods outperform the parataxonomist (19% underestimation; 31.6% taxonomic accuracy). The number of species found in more than one sampling area was highest in the Eastern Highlands and Huon (Sørensen similarity index 0.07, 4 shared species); ⅓ of all areas had no species overlap. Success rates of DNA barcoding methods were lowest when species showed a pronounced geographical structure. In general, Trigonopterus show high α and β-diversity across New Guinea.
DNA barcoding is an excellent tool for biodiversity surveys but success rates might drop when closer localities are included. Hyperdiverse Trigonopterus are a useful taxon for evaluating forest remnants in Melanesia, allowing finer-grained analyses than would be possible with vertebrate taxa commonly used to date. Our protocol should help establish other groups of hyperdiverse fauna as target taxa for community ecology. Sequencing delivers objective data on taxa of incredible diversity but mostly without a solid taxonomic foundation and should help pave the road for the eventual formal naming of new species
Identification of Potent Odorants in a Novel Nonalcoholic Beverage Produced by Fermentation of Wort with Shiitake (Lentinula edodes)
Novel
refreshments with pleasant flavors were developed by fermentation
of wort with basidiomycetes. Among 31 screened fungi, shiitake (Lentinula edodes) produced the most pleasant flavor.
It was perceived as fruity, slightly sour, and plum-like. Flavor compounds
were isolated by liquid–liquid extraction (LLE) and by headspace
solid phase microextraction (HS-SPME). The key odor-active compounds
were analyzed by a gas chromatography system equipped with a tandem
mass spectrometry detector and an olfactory detection port (GC-MS/MS-O)
and aroma extract dilution analysis (AEDA). For HS-SPME, a revised
method of increasing the GC inlet split ratio was used. Most of the
key odor-active compounds (e.g., 2-acetylpyrrole, β-damascenone,
(<i>E</i>)-2-nonenal, and 2-phenylethanol) were detected
with both extraction techniques. However, distinct differences between
these two methods were observed
NaClO-Generated Iron(IV)oxo and Iron(V)oxo TAMLs in Pure Water
The unique properties
of entirely aliphatic TAML activator [Fe<sup>III</sup>{(Me<sub>2</sub>C<i>N</i>COCMe<sub>2</sub><i>N</i>CO)<sub>2</sub>CMe<sub>2</sub>}OH<sub>2</sub>]<sup>−</sup> (<b>3</b>), namely the increased steric bulk of the ligand
and the unmatched resistance to the acid-induced demetalation, enables
the generation of high-valent iron derivatives in pure water at any
pH. An iron(V)oxo species is readily produced with NaClO at pH values
from 2 to 10.6 without any observable intermediate. This is the first
reported example of iron(V)oxo formed in pure water. At pH 13, iron(V)oxo
is not formed and NaClO oxidizes <b>3</b> to an iron(IV)oxo
derivative
Biochemical and structural characterization of the glycosylase domain of MBD4 bound to thymine and 5-hydroxymethyuracil-containing DNA
A “Beheaded” TAML Activator: A Compromised Catalyst that Emphasizes the Linearity between Catalytic Activity and p<i>K</i><sub>a</sub>
Studies
of the new tetra-amido macrocyclic ligand (TAML) activator [Fe<sup>III</sup>{(Me<sub>2</sub>C<i>N</i>COCMe<sub>2</sub><i>N</i>CO)<sub>2</sub>CMe<sub>2</sub>}OH<sub>2</sub>]<sup>−</sup> (<b>4</b>) in water in the pH range of 2–13 suggest
its pseudo-octahedral geometry with two nonequivalent axial H<sub>2</sub>O ligands and revealed (i) the anticipated basic drift of
the first p<i>K</i><sub>a</sub> of water to 11.38 due to
four electron-donating methyl groups alongside (ii) its counterintuitive
enhanced resistance to acid-induced iron(III) ejection from the macrocycle.
The catalytic activity of <b>4</b> in the oxidation of Orange
II (S) by H<sub>2</sub>O<sub>2</sub> in the pH range of 7–12
is significantly lower than that of previously reported TAML activators,
though it follows the common rate law (<i>v</i>/[Fe<sup>III</sup>] = <i>k</i><sub>I</sub><i>k</i><sub>II</sub>[H<sub>2</sub>O<sub>2</sub>][S]/(<i>k</i><sub>I</sub>[H<sub>2</sub>O<sub>2</sub>] + <i>k</i><sub>II</sub>[S])
and typical pH profiles for <i>k</i><sub>I</sub> and <i>k</i><sub>II</sub>. At pH 7 and 25 °C the rate constants <i>k</i><sub>I</sub> and <i>k</i><sub>II</sub> equal
0.63 ± 0.02 and 1.19 ± 0.03 M<sup>–1</sup> s<sup>–1</sup>, respectively. With these new values for p<i>K</i><sub>a</sub>, <i>k</i><sub>I</sub> and <i>k</i><sub>II</sub> establishing new high and low limits, respectively,
the rate constants <i>k</i><sub>I</sub> and <i>k</i><sub>II</sub> were correlated with p<i>K</i><sub>a</sub> values of all TAML activators. The relations log <i>k</i> = log <i>k</i><sup>0</sup> + α × p<i>K</i><sub>a</sub> were established with log <i>k</i><sup>0</sup> = 13 ± 2 and 20 ± 4 and α = −1.1 ± 0.2
and −1.8 ± 0.4 for <i>k</i><sub>I</sub> and <i>k</i><sub>II</sub>, respectively. Thus, the reactivity of TAML
activators across four generations of catalysts is predictable through
their p<i>K</i><sub>a</sub> values
Activation of Dioxygen by a TAML Activator in Reverse Micelles: Characterization of an Fe<sup>III</sup>Fe<sup>IV</sup> Dimer and Associated Catalytic Chemistry
Iron TAML activators of peroxides
are functional catalase-peroxidase
mimics. Switching from hydrogen peroxide (H<sub>2</sub>O<sub>2</sub>) to dioxygen (O<sub>2</sub>) as the primary oxidant was achieved
by using a system of reverse micelles of Aerosol OT (AOT) in <i>n</i>-octane. Hydrophilic TAML activators are localized in the
aqueous microreactors of reverse micelles where water is present in
much lower abundance than in bulk water. <i>n</i>-Octane
serves as a proximate reservoir supplying O<sub>2</sub> to result
in partial oxidation of Fe<sup>III</sup> to Fe<sup>IV</sup>-containing
species, mostly the Fe<sup>III</sup>Fe<sup>IV</sup> (major) and Fe<sup>IV</sup>Fe<sup>IV</sup> (minor) dimers which coexist with the Fe<sup>III</sup> TAML monomeric species. The speciation depends on the pH
and the degree of hydration <i>w</i><sub>0</sub>, viz.,
the amount of water in the reverse micelles. The previously unknown
Fe<sup>III</sup>Fe<sup>IV</sup> dimer has been characterized by UV–vis,
EPR, and Mössbauer spectroscopies. Reactive electron donors
such as NADH, pinacyanol chloride, and hydroquinone undergo the TAML-catalyzed
oxidation by O<sub>2</sub>. The oxidation of NADH, studied in most
detail, is much faster at the lowest degree of hydration <i>w</i><sub>0</sub> (in “drier micelles”) and is accelerated
by light through NADH photochemistry. Dyes that are more resistant
to oxidation than pinacyanol chloride (Orange II, Safranine O) are
not oxidized in the reverse micellar media. Despite the limitation
of low reactivity, the new systems highlight an encouraging step in
replacing TAML peroxidase-like chemistry with more attractive dioxygen-activation
chemistry