•An ensemble-based co-training approach, named ECoRec, is proposed.•ECoRec process data from two or more different views to create a more robust model.•Our approach provide an enriched matrix that ...alleviate the sparsity and cold-start problems.•Results show that our strategy improves the overall system’s performance.
Collaborative Filtering (CF) is one of the best performing and most widely used approaches for recommender systems. Although significant progress has been made in this area, current CF methods still suffer from cold-start and sparsity problems. A primary issue is that the fraction of users willing to rate items tends to be very small in most practical applications, which causes the number of users and/or items with few or no interactions in recommendation databases to be large. As a direct consequence of ratings sparsity, recommender algorithms may provide poor recommendations (reducing accuracy) or decline recommendations (reducing coverage). This paper proposes an ensemble scheme based on a co-training approach, named ECoRec, that drives two or more recommenders to agree with each others’ predictions to generate their own. The experiments on eight real-life public databases show that better accuracy can be obtained when recommender algorithms are simultaneously trained from multiple views and combined into an ensemble to make predictions.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Purpose
Basilar artery is the second most common site of fenestration, after the anterior communicating region. It is believed this variation predisposes a patient to posterior aneurysm formation and ...increases the complexity of the surgical anatomy. Endovascular management has become the first option to treat these aneurysms. We retrospectively evaluated eight patients, who underwent endovascular treatment for fenestrated basilar artery related aneurysms (fBA-AN). Additionally, based on our findings and on literature review, we developed a treatment strategy based on a proposed classification of fBA-AN.
Methods
Between June 2010 and September 2012, eight patients harboring nine basilar artery fenestration aneurysms were consecutively treated. Based on aneurysm morphology (neck size) and its relationship to the fenestration (sparing or not one channel) characterized by 3D-DSA, we proposed a simple classification and treatment strategies. Additionally, a literature review was performed.
Results
All patients received endovascular treatment. Most aneurysms involved the vertebrobasilar junction and both channels of the fenestration. A total of 5 aneurysms had wide neck while 4 had narrow neck. Overall, 5 (55.5 %) aneurysms were treated with stent assisted coiling, 3 (33.3 %) aneurysms with selective coiling, and 1 (11.1 %) aneurysm with balloon assisted coiling. We had only 1 (11.1 %) complication, named aneurysm rupture.
Conclusion
Basilar artery fenestration aneurysms are rare and complex lesions. Endovascular treatment appears to be safe and efficient. The detailed understanding of the aneurysm morphology and its relation to the fenestration is strongly recommended to treatment planning. Further studies are necessary to validate the utility of the proposed classification and treatment strategy.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
We present new constraints on dark matter interactions using 1.7 years of COSINE-100 data. The COSINE-100 experiment, consisting of 106 kg of tallium-doped sodium iodide NaI(Tl) target material, is ...aimed to test DAMA’s claim of dark matter observation using the same NaI(Tl) detectors. Improved event selection requirements, a more precise understanding of the detector background, and the use of a larger dataset considerably enhance the COSINE-100 sensitivity for dark matter detection. No signal consistent with the dark matter interaction is identified and rules out model-dependent dark matter interpretations of the DAMA signals in the specific context of standard halo model with the same NaI(Tl) target for various interaction hypotheses.
COSINE-100 is a dark matter direct detection experiment with 106kg NaI(Tl) as the target material. 210Pb and daughter isotopes are a dominant background in the WIMP region of interest and are ...detected via β decay and α decay. Analysis of the α channel complements the background model as observed in the β/γ channel. We present the measurement of the quenching factors and Monte Carlo simulation results and activity quantification of the α decay components of the COSINE-100 NaI(Tl) crystals. The data strongly indicate that the α decays probabilistically undergo two possible quenching factors but require further investigation. The fitted results are consistent with independent measurements and improve the overall understanding of the COSINE-100 backgrounds. Furthermore, the half-life of 216Po has been measured to be 143.4±1.2ms, which is consistent with and more precise than most current measurements.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The etiology of age-related olfactory loss is still unclear, but it has been claimed that polypharmacotherapy may contribute to olfactory dysfunction, particularly in the elderly, who are more likely ...to need multiple drugs. The present pilot study investigated the relationship between smell and the number and type of drugs taken in a group of elderly.
50 elderly volunteers (over 64 years old) who were healthy from the sinonasal standpoint (SNOT-22 under 1) and had no cognitive impairments Mini Mental State Examination (MMSE over 18) were administered the Screening 12 test and tested on their n-butanol olfactory threshold. Their olfactory performance was then connected with the number and type of drugs participants used.
The mean age of the included volunteers was 74 plus/minus 7 years. No association emerged between odor identification and number of drugs taken. The number of drugs taken correlated directly with a worse olfactory threshold and with a worse MMSE score, meaning a worse cognitive status. Odor identification significantly worsened with age. Comparing those volunteers taking only one drug known to not influence olfaction with another sub-group of volunteers taking five or more drugs, it was evident that subjects taking only one drug scored significantly better in olfactory threshold test and MMSE, and marginally better in olfactory identification test. For what concerns the difference between male and female volunteers, no difference in olfactory test result was shown, both for threshold and identification. Univariate analysis showed a direct correlation between the consumption of calcium channel blockers, beta-blockers, acetylsalicylic acid and olfactory threshold, meaning a worse sense of smell. Acetylsalicylic acid also correlated inversely with odor identification, meaning again a worse sense of smell, and so did potassium-sparing diuretics. Multivariate analysis showed that MMSE scores correlated with a better sense of smell, that is a lower olfactory threshold, and that beta-blockers and acetylsalicylic acid negatively affected olfactory threshold, meaning a worse sense of smell. Acetylsalicylic acid also correlated inversely with odor identification, meaning again a worse sense of smell.
The number of drugs taken demonstrated to be significantly correlated with a worse olfactory threshold and worse MMSE. Larger studies on elderly volunteers are needed to confirm these preliminary findings.
Digital Image Correlation (DIC) is a non-contact full-field image analysis technique which allows to retrieve strains and displacements in three dimensions at the surface of any type of material and ...under arbitrary loading. In recent years, high-speed and high-resolution cameras have been developed for static as well as for dynamic applications. As consequence, the application fields for DIC have broadened and it has proven to be a flexible and very accurate measurement solution for deformation analysis and material characterization. Nevertheless, nowadays DIC is often used in a qualitative manner rather than as a metrological tool. This is especially due to the time-consuming task related to the post-processing of the images. When compared to other vibration testing techniques, full-field approaches (such as DIC) allow a greater flexibility by providing a very dense number of experimental data over a single measurement. Another advantage is related to the fact that the geometry is automatically extracted from the images. In this paper, the possibility to combine global acceleration measurements on a small component with local full-field standard machine vision quasi-static camera measurements is investigated. In particular, the regularization properties of DIC and their impact on modal analysis will be studied in detail. Strains and displacements could be used in a second stage for modal analysis purpose in order to characterize the dynamic behaviour of the specimen in a certain frequency range. Different approaches could be used for combining together the data obtained during the tests. The most obvious approach would be the alignment of the time histories based on reference signals for Frequency Response Functions (FRFs) calculation prior to perform any further processing. Unfortunately this is not always possible because of synchronization issues. An alternative possibility, in case broadband random excitation is used, requires to process time data into auto and crosspowers and identify the modal parameters by using Operational Modal Analysis (OMA).
COSINE-100 is a direct detection dark matter search experiment that uses a 106 kg array of eight NaI(Tl) crystals that are kept underground at the Yangyang Underground Laboratory to avoid cosmogenic ...activation of radioisotopes by cosmic rays. Even though the cosmogenic activity is declining with time, there are still significant background rates from the remnant nuclides. In this paper, we report measurements of cosmogenic isotope contaminations with less than one year half-lives that are based on extrapolations of the time dependent activities of their characteristic energy peaks to activity rates at the time the crystals were deployed underground. For longer-lived 109Cd (T1/2=1.27 y) and 22Na (T1/2=2.6 y), we investigate time correlations and coincidence events due to several emissions. The inferred sea-level production rates are compared with calculations based on the ACTIVIA and MENDL-2 model calculations and experimental data. The results from different approaches are in reasonable agreement with each other. For 3H, which has a long, 12.3 year half-life, we evaluated the activity levels and the exposure times that are in reasonable agreement with the time period estimated for each crystal’s exposure.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The DAMA/LIBRA collaboration has reported the observation of an annual modulation in the event rate that has been attributed to dark matter interactions over the last two decades. However, even ...though tremendous efforts to detect similar dark matter interactions were pursued, no definitive evidence has been observed to corroborate the DAMA/LIBRA signal. Many studies assuming various dark matter models have attempted to reconcile DAMA/LIBRA's modulation signals and null results from other experiments, however no clear conclusion can be drawn. Apart from the dark matter hypothesis, several studies have examined the possibility that the modulation is induced by variations in detector's environment or their specific analysis methods. In particular, a recent study presents a possible cause of the annual modulation from an analysis method adopted by the DAMA/LIBRA experiment in which the observed annual modulation could be reproduced by a slowly varying time-dependent background. Here, we study the COSINE-100 data using an analysis method similar to the one adopted by the DAMA/LIBRA experiment and observe a significant annual modulation, however the modulation phase is almost opposite to that of the DAMA/LIBRA data. Assuming the same background composition for COSINE-100 and DAMA/LIBRA, simulated experiments for the DAMA/LIBRA without dark matter signals also provide significant annual modulation with an amplitude similar to DAMA/LIBRA with opposite phase. Even though this observation does not directly explain the DAMA/LIBRA results directly, this interesting phenomenon motivates more profound studies of the time-dependent DAMA/LIBRA background data.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
We report the identification of metastable isomeric states of
228
Ac at 6.28 keV, 6.67 keV and 20.19 keV, with lifetimes of an order of 100 ns. These states are produced by the
β
-decay of
228
Ra, a ...component of the
232
Th decay chain, with
β
Q-values of 39.52 keV, 39.13 keV and 25.61 keV, respectively. Due to the low Q-value of
228
Ra as well as the relative abundance of
232
Th and their progeny in low background experiments, these observations potentially impact the low-energy background modeling of dark matter search experiments.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Water treatment plants (WTP) in the City of Manaus, Brazil, generate tons of sludge daily, which are then disposed of in landfills and main watercourses, particularly two important Amazonian Rivers: ...the blackwater Negro River and the pale sandy-colored water Solimões River. Because WTP-based sludges are rich in silicon and aluminum, they have been employed in the synthesis of geopolymers - alkaline activated inorganic polymers consisting of silicate and aluminosilicate chains. This paper reports the results of a geopolymeric synthesis process in which calcined sludge was explored as a source of silica and alumina. In this research, a laboratory testing program was developed to characterize the waste material generated from a water treatment plant in Manaus, whose intake water is influenced by the above referred rivers. Sample preparation involved kiln drying at 110 °C for 8 h, grinding in ball mill for 2 h, and calcination at 750 °C for 6 h. The calcined sludge was used as precursor, and potassium hydroxide added as activating alkali. Two geopolymers, one from each sludge source, were prepared following identical procedures. The chemical, compositional, morphological, thermal and mechanical properties of the fresh and hardened geopolymers were characterized. The geopolymers reached uniaxial compressive strengths of over 50 MPa at 28 days. Calcination conveyed more refined properties to the sludge-based geopolymers, akin to metakaolin-based geopolymers. The results presented herein support the technical feasibility of geopolymer synthesis in the lab scale.
•Sludge from the water treatment process was used in the production of geopolymers.•The geopolymers were cured at room temperature.•In the thermal tests, the geopolymers showed signs of refractory behavior.•Mechanical strength tests showed values up to 79 MPa at 28 days of cure.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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