6,237 research outputs found
Characterisation of thermal crosstalk-induced wavelength shift in a monolithic InP dual DFB lasers PIC
We present dual DFB lasers each integrated with one heater developed in a generic foundry platform. The thermal effects are experimentally investigated and exhibited a continuous wavelength difference tuning of 0-12.33 nm
Emulsifier and antioxidant properties of by-products obtained by enzymatic degumming of soybean oil
The enzymes used in degumming, called phospholipases, specifically act on phospholipids without degrading the oil itself. Degumming using a phospholipase C enzyme allows to meet all market specifications while it increases the oil yield. The aim of this study was to evaluate antioxidant and emulsifier properties of the recovered gum (RG) obtained by enzymatic oil degumming process of crude soybean oil subjected to modifications as deoiling (RG deoiled) or ethanol fractionation (RG soluble and insoluble). RG soluble allowed obtaining more stable O/W emulsions (30:70 w/w) in comparison with those by-products assayed at different concentrations (0.1?1.0%). Also, deoiled soybean lecithin (DSL) andRG deoiled had a similar behavior in relation to the kinetic destabilization (%BS profiles), despite the different degumming processes used to obtain these samples. The study on induction times (Metrohm Rancimat) showed a significant antioxidant effect (p<0.05) against a refined sunflower oil associated with all the by-products analyzed. However, RG soluble and DSL showed a strong effect on the oil stability at high concentrations (1000?2000 ppm). These results showed that the deoiled recovered gum and its derivates obtained by ethanol fractionation are a potential alternative for industrial application as additive.Fil: Cabezas, Dario Marcelino. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Universidad Nacional de la Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Diehl, B. W. K.. Spectral Service GmbH Laboratorium fur Auftragsanalytik. Cologne; AlemaniaFil: Tomas, Mabel Cristina. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Universidad Nacional de la Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin
Debris Disks: Probing Planet Formation
Debris disks are the dust disks found around ~20% of nearby main sequence
stars in far-IR surveys. They can be considered as descendants of
protoplanetary disks or components of planetary systems, providing valuable
information on circumstellar disk evolution and the outcome of planet
formation. The debris disk population can be explained by the steady
collisional erosion of planetesimal belts; population models constrain where
(10-100au) and in what quantity (>1Mearth) planetesimals (>10km in size)
typically form in protoplanetary disks. Gas is now seen long into the debris
disk phase. Some of this is secondary implying planetesimals have a Solar
System comet-like composition, but some systems may retain primordial gas.
Ongoing planet formation processes are invoked for some debris disks, such as
the continued growth of dwarf planets in an unstirred disk, or the growth of
terrestrial planets through giant impacts. Planets imprint structure on debris
disks in many ways; images of gaps, clumps, warps, eccentricities and other
disk asymmetries, are readily explained by planets at >>5au. Hot dust in the
region planets are commonly found (<5au) is seen for a growing number of stars.
This dust usually originates in an outer belt (e.g., from exocomets), although
an asteroid belt or recent collision is sometimes inferred.Comment: Invited review, accepted for publication in the 'Handbook of
Exoplanets', eds. H.J. Deeg and J.A. Belmonte, Springer (2018
Mobile Communication Signatures of Unemployment
The mapping of populations socio-economic well-being is highly constrained by
the logistics of censuses and surveys. Consequently, spatially detailed changes
across scales of days, weeks, or months, or even year to year, are difficult to
assess; thus the speed of which policies can be designed and evaluated is
limited. However, recent studies have shown the value of mobile phone data as
an enabling methodology for demographic modeling and measurement. In this work,
we investigate whether indicators extracted from mobile phone usage can reveal
information about the socio-economical status of microregions such as districts
(i.e., average spatial resolution < 2.7km). For this we examine anonymized
mobile phone metadata combined with beneficiaries records from unemployment
benefit program. We find that aggregated activity, social, and mobility
patterns strongly correlate with unemployment. Furthermore, we construct a
simple model to produce accurate reconstruction of district level unemployment
from their mobile communication patterns alone. Our results suggest that
reliable and cost-effective economical indicators could be built based on
passively collected and anonymized mobile phone data. With similar data being
collected every day by telecommunication services across the world,
survey-based methods of measuring community socioeconomic status could
potentially be augmented or replaced by such passive sensing methods in the
future
Gauss-Bonnet Black Holes and Heavy Fermion Metals
We consider charged black holes in Einstein-Gauss-Bonnet Gravity with
Lifshitz boundary conditions. We find that this class of models can reproduce
the anomalous specific heat of condensed matter systems exhibiting
non-Fermi-liquid behaviour at low temperatures. We find that the temperature
dependence of the Sommerfeld ratio is sensitive to the choice of Gauss-Bonnet
coupling parameter for a given value of the Lifshitz scaling parameter. We
propose that this class of models is dual to a class of models of
non-Fermi-liquid systems proposed by Castro-Neto et.al.Comment: 17 pages, 6 figures, pdfLatex; small corrections to figure 10 in this
versio
First direct observation of the Van Hove singularity in the tunneling spectra of cuprates
In two-dimensional lattices the electronic levels are unevenly spaced, and
the density of states (DOS) displays a logarithmic divergence known as the Van
Hove singularity (VHS). This is the case in particular for the layered cuprate
superconductors. The scanning tunneling microscope (STM) probes the DOS, and is
therefore the ideal tool to observe the VHS. No STM study of cuprate
superconductors has reported such an observation so far giving rise to a debate
about the possibility of observing directly the normal state DOS in the
tunneling spectra. In this study, we show for the first time that the VHS is
unambiguously observed in STM measurements performed on the cuprate Bi-2201.
Beside closing the debate, our analysis proves the presence of the pseudogap in
the overdoped side of the phase diagram of Bi-2201 and discredits the scenario
of the pseudogap phase crossing the superconducting dome.Comment: 4 pages, 4 figure
Epidemiological determinants of spread of causal agent of severe acute respiratory syndrome in Hong Kong.
BACKGROUND: Health authorities worldwide, especially in the Asia Pacific region, are seeking effective public-health interventions in the continuing epidemic of severe acute respiratory syndrome (SARS). We assessed the epidemiology of SARS in Hong Kong. METHODS: We included 1425 cases reported up to April 28, 2003. An integrated database was constructed from several sources containing information on epidemiological, demographic, and clinical variables. We estimated the key epidemiological distributions: infection to onset, onset to admission, admission to death, and admission to discharge. We measured associations between the estimated case fatality rate and patients' age and the time from onset to admission. FINDINGS: After the initial phase of exponential growth, the rate of confirmed cases fell to less than 20 per day by April 28. Public-health interventions included encouragement to report to hospital rapidly after the onset of clinical symptoms, contact tracing for confirmed and suspected cases, and quarantining, monitoring, and restricting the travel of contacts. The mean incubation period of the disease is estimated to be 6.4 days (95% CI 5.2-7.7). The mean time from onset of clinical symptoms to admission to hospital varied between 3 and 5 days, with longer times earlier in the epidemic. The estimated case fatality rate was 13.2% (9.8-16.8) for patients younger than 60 years and 43.3% (35.2-52.4) for patients aged 60 years or older assuming a parametric gamma distribution. A non-parametric method yielded estimates of 6.8% (4.0-9.6) and 55.0% (45.3-64.7), respectively. Case clusters have played an important part in the course of the epidemic. INTERPRETATION: Patients' age was strongly associated with outcome. The time between onset of symptoms and admission to hospital did not alter outcome, but shorter intervals will be important to the wider population by restricting the infectious period before patients are placed in quarantine
On the classification of OADP varieties
The main purpose of this paper is to show that OADP varieties stand at an
important crossroad of various main streets in different disciplines like
projective geometry, birational geometry and algebra. This is a good reason for
studying and classifying them. Main specific results are: (a) the
classification of all OADP surfaces (regardless to their smoothness); (b) the
classification of a relevant class of normal OADP varieties of any dimension,
which includes interesting examples like lagrangian grassmannians. Following
[PR], the equivalence of the classification in (b) with the one of
quadro-quadric Cremona transformations and of complex, unitary, cubic Jordan
algebras are explained.Comment: 13 pages. Dedicated to Fabrizio Catanese on the occasion of his 60th
birthday. To appear in a special issue of Science in China Series A:
Mathematic
To dash or to dawdle: verb-associated speed of motion influences eye movements during spoken sentence comprehension
In describing motion events verbs of manner provide information about the speed of agents or objects in those events. We used eye tracking to investigate how inferences about this verb-associated speed of motion would influence the time course of attention to a visual scene that matched an event described in language. Eye movements were recorded as participants heard spoken sentences with verbs that implied a fast (“dash”) or slow (“dawdle”) movement of an agent towards a goal. These sentences were heard whilst participants concurrently looked at scenes depicting the agent and a path which led to the goal object. Our results indicate a mapping of events onto the visual scene consistent with participants mentally simulating the movement of the agent along the path towards the goal: when the verb implies a slow manner of motion, participants look more often and longer along the path to the goal; when the verb implies a fast manner of motion, participants tend to look earlier at the goal and less on the path. These results reveal that event comprehension in the presence of a visual world involves establishing and dynamically updating the locations of entities in response to linguistic descriptions of events
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