1,284 research outputs found
Designing Bioinspired Robots Editorial
This IJARS issue is dedicated to a new international conference series, which has been promoted by ENEA and IARP (International Advanced Robotics Programme). The first conference, entitled Bio-inspired Robotics, was held on 14th-15th May 2014 at the ENEA's Frascati Centre. The conference was dedicated to young researchers and scholars with promising ideas, methods and products for innovation and technology transfer in the field of service robots with bio-inspired design and operation
Learning Relatedness Measures for Entity Linking
Entity Linking is the task of detecting, in text documents, relevant mentions to entities of a given knowledge base. To this end, entity-linking algorithms use several signals and features extracted from the input text or from the knowl- edge base. The most important of such features is entity relatedness. Indeed, we argue that these algorithms benefit from maximizing the relatedness among the relevant enti- ties selected for annotation, since this minimizes errors in disambiguating entity-linking.
The definition of an e↵ective relatedness function is thus a crucial point in any entity-linking algorithm. In this paper we address the problem of learning high-quality entity relatedness functions. First, we formalize the problem of learning entity relatedness as a learning-to-rank problem. We propose a methodology to create reference datasets on the basis of manually annotated data. Finally, we show that our machine-learned entity relatedness function performs better than other relatedness functions previously proposed, and, more importantly, improves the overall performance of dif- ferent state-of-the-art entity-linking algorithms
On Suggesting Entities as Web Search Queries
The Web of Data is growing in popularity and dimension,
and named entity exploitation is gaining importance in many research
fields. In this paper, we explore the use of entities that can be extracted
from a query log to enhance query recommendation. In particular, we
extend a state-of-the-art recommendation algorithm to take into account
the semantic information associated with submitted queries. Our novel
method generates highly related and diversified suggestions that we as-
sess by means of a new evaluation technique. The manually annotated
dataset used for performance comparisons has been made available to
the research community to favor the repeatability of experiments
A theoretical investigation of the reaction between the amidogen, NH, and the ethyl, C2H5, radicals: a possible gas-phase formation route of interstellar and planetary ethanimine
The reaction between the amidogen, NH, radical and the ethyl, C2H5, radical
has been investigated by performing electronic structure calculations of the
underlying doublet potential energy surface. Rate coefficients and product
branching ratios have also been estimated by combining capture and RRKM
calculations. According to our results, the reaction is very fast, close to the
gas-kinetics limit. However, the main product channel, with a yield of ca.
86-88% in the range of temperatures investigated, is the one leading to
methanimine and the methyl radical. The channels leading to the two E-, Z-
stereoisomers of ethanimine account only for ca. 5-7% each. The resulting ratio
[E-CH3CHNH]/[Z-CH3CHNH] is ca. 1.2, that is a value rather lower than that
determined in the Green Bank Telescope PRIMOS radio astronomy survey spectra of
Sagittarius B2 North (ca. 3). Considering that ice chemistry would produce
essentially only the most stable isomer, a possible conclusion is that the
observed [E-CH3CHNH]/[Z-CH3CHNH] ratio is compatible with a combination of
gas-phase and grain chemistry. More observational and laboratory data are
needed to definitely address this issue
An evaluation of unit nonresponse bias in the Italian Households Budget Survey
Die Auswirkungen von Antwortverweigerung sind in der Literatur zur Umfrageforschung vielfach diskutiert worden. Antwortverweigerung führt zu einer Erhöhung der Stichprobenvarianz, deren Ausmaß über die Schätzung der durch Antwortverweigerung verursachten Verzerrung gemessen werden kann. Wenn Befragte nur unvollkommen kooperieren, führt dies zu ungenauen oder unvollständigen Informationen, die nicht zum Zweck einer Schätzung herangezogen werden können. Istat streicht seit 1991 alle Haushalte mit inkompatiblen Daten für Ausgaben und Einkommen aus seiner Stichprobe. Die Verfasser bezeichnen diese Gruppe als "unzuverlässige Respondenten". Solche Daten eignen sich zwar nicht für Schätzungen, sie erlauben jedoch Rückschlüsse auf die Gruppe der Antwortverweigerer. Dem liegt die Annahme zu Grunde, dass die Gruppe der unzuverlässigen Respondenten eher der Gruppe der Antwortverweigerer ähnelt als der Gruppe der Antwortenden. Die Verfasser berichten über den Versuch, den durch Antwortverweigerung entstandenen Bias im Italian Household Budget Survey 1995 zu bestimmen. Hierzu wurde keine gesonderte Untersuchung der Nonrespondenten durchgeführt. (ICEÜbers)"The effect of nonresponse is a crucial aspect which has received considerable attention in literature. Nonresponse causes an increase in sampling variance and the estimates of units nonresponse bias are useful to give a concrete measure of this increase. Scarce co-operation of respondents gives inaccurate or incomplete information, and this part of the answers can't be used in the estimation. Since 1991, Istat erases from its sample file all households with incompatible data on expenditure and income. The authors call this the 'UR (Unreliable Respondents) sub population'. UR data can't be used to build estimates, but can be used to give approximate information an NR. The idea is that, concerning behaviour, the NR population is more similar to UR than to R. The results of an attempt to evaluate unit nonresponse bias in the 1995 Italien Household Budget Survey (HBS) are shown in this paper. These results were obtained without performing a specific survey on nonrespondents." (author's abstract
Discovering Europeana users’ search behavior
Europeana is a strategic project funded by the European Commission with the goal of making Europe's cultural and scientific heritage accessible to the public. ASSETS is a two-year Best Practice Network co-funded by the CIP PSP Programme to improve performance, accessibility and usability of the Europeana search engine. Here we present a characterization of the Europeana logs by showing statistics on common behavioural patterns of the Europeana users
Interstellar dimethyl ether gas-phase formation: a quantum chemistry and kinetics study
Dimethyl ether is one of the most abundant interstellar complex organic
molecules. Yet its formation route remains elusive. In this work, we have
performed electronic structure and kinetics calculations to derive the rate
coefficients for two ion-molecule reactions recently proposed as a gas-phase
formation route of dimethyl ether in interstellar objects, namely CHOH +
CHOH (CH)OH + HO followed by
(CH)OH + NH CHOCH + NH. A
comparison with previous experimental rate coefficients for the reaction
CHOH + CHOH sustains the accuracy of the present calculations and
allow a more reliable extrapolation at the low temperatures of interest in
interstellar objects (10-100 K). The rate coefficient for the reaction
(CH)OH + NH is, instead, provided for the first time ever. The
rate coefficients derived in this work essentially confirm the prediction by
Taquet et al. (2016) concerning dimethyl ether formation in hot cores/corinos.
Nevertheless, this formation route cannot be efficient in cold objects (like
prestellar cores) where dimethyl ether is also detected, because ammonia has a
very low abundance in those environments
The genealogical tree of ethanol: gas-phase formation of glycolaldehyde, acetic acid and formic acid
Despite the harsh conditions of the interstellar medium, chemistry thrives in
it, especially in star forming regions where several interstellar complex
organic molecules (iCOMs) have been detected. Yet, how these species are
synthesised is a mystery. The majority of current models claim that this
happens on interstellar grain surfaces. Nevertheless, evidence is mounting that
neutral gas-phase chemistry plays an important role. In this article, we
propose a new scheme for the gas-phase synthesis of glycolaldehyde, a species
with a prebiotic potential and for which no gas-phase formation route was
previously known. In the proposed scheme, the ancestor is ethanol and the
glycolaldehyde sister species are acetic acid (another iCOM with unknown
gas-phase formation routes) and formic acid. For the reactions of the new
scheme with no available data, we have performed electronic structure and
kinetics calculations deriving rate coefficients and branching ratios.
Furthermore, after a careful review of the chemistry literature, we revised the
available chemical networks, adding and correcting several reactions related to
glycolaldehyde, acetic acid and formic acid. The new chemical network has been
used in an astrochemical model to predict the abundance of glycolaldehyde,
acetic acid and formic acid. The predicted abundance of glycolaldehyde depends
on the ethanol abundance in the gas phase and is in excellent agreement with
the measured one in hot corinos and shock sites. Our new model overpredicts the
abundance of acetic acid and formic acid by about a factor of ten, which might
imply a yet incomplete reaction network
Arsenic and germanium determination by hydride generation in the D.C. plasma optical emission spectrometer
Modifications to the commercial hydride generator,
manufactured by Spectrametrics, resulted in improved operating
procedure and enhancement of the arsenic and germanium signals.
Experiments with arsenic(III) and arsenic(V) showed that
identical reiults could be produced from both oxidation states.
However, since arsenic(V) is reduced more slowly than
arsenic(III), peak areas and not peak heights must be measured
when the arsine is immediately stripped from the system
(approximately 5 seconds reaction). When the reduction is
allowed to proceed for 20 seconds before the arsine is stripped,
peak heights may be used. For a 200 ng/mL solution, the
relative standard deviation is 2.8% for As(III) and 3.8% for
As(V). The detection limit for arsenic using the modified
system is 0.50 ng/mL.
Studies performed on As(V) standards show that the
interferences from 1000 mg/L of nickel(II), cobalt(II),
iron(III), copper(II), cadmium(II), and zinc(II) can be
eliminated with the aid of 5 M Hel and 3% L-cystine.
Conditions for the reduction of germanium to the
corresponding hydride were investigated. The effect of
different concentrations of HCl on the reduction of germanium to
the covalent hydride in aqueous media by means of NaBH
4
solutions was assessed. Results show that the best response is
accomplished at a pH of 1.7. The use of buffer solutions was
similarly characterized. In both cases, results showed that the element is best reduced when the final pH of the solution after
reaction is almost neutral. In addition, a more sensitive
method, which includes the use of (NH4)2S208' has been developed.
A 20% increase in the germanium signal is registered when
compared to the signal achieved with Hel alone. Moreover, under
these conditions, reduction of germanium could be accomplished,
even when the solution's pH is neutral. For a 100 ng/mL
germanium standard the rsd is 3%. The detection limit for
germanium in 0.05 M Hel medium (pH 1.7) is 0.10 ng/mL and 0.09
ng/mL when ammonium persulphate is used in conjunction with Hel.
Interferences from 1000 mg/L of iron(III), copper(II),
cobalt(II), nickel(II), cadmium(II), lead(II), mercury(II),
aluminum(III), tin(IV), arsenic(III), arsenic(V) and zinc(II)
were studied and characterized. In this regard, the use of
(NH4)ZS20S and Hel at a pH of 1.7 proved to be a successful
mixture in the sbppression of the interferences caused by iron,
copper, aluminum, tin, lead, and arsenic. The method was applied
to the determination of germanium in cherts and iron ores.
In addition, experiments with tin(IV) showed that a 15%
increase in the tin signal can be accomplished in the presence of
1 mL of (NH4)2S20S 10% (m/V)
- …