55 research outputs found
Improving package recommendations through query relaxation
Recommendation systems aim to identify items that are likely to be of
interest to users. In many cases, users are interested in package
recommendations as collections of items. For example, a dietitian may wish to
derive a dietary plan as a collection of recipes that is nutritionally
balanced, and a travel agent may want to produce a vacation package as a
coordinated collection of travel and hotel reservations. Recent work has
explored extending recommendation systems to support packages of items. These
systems need to solve complex combinatorial problems, enforcing various
properties and constraints defined on sets of items. Introducing constraints on
packages makes recommendation queries harder to evaluate, but also harder to
express: Queries that are under-specified produce too many answers, whereas
queries that are over-specified frequently miss interesting solutions.
In this paper, we study query relaxation techniques that target package
recommendation systems. Our work offers three key insights: First, even when
the original query result is not empty, relaxing constraints can produce
preferable solutions. Second, a solution due to relaxation can only be
preferred if it improves some property specified by the query. Third,
relaxation should not treat all constraints as equals: some constraints are
more important to the users than others. Our contributions are threefold: (a)
we define the problem of deriving package recommendations through query
relaxation, (b) we design and experimentally evaluate heuristics that relax
query constraints to derive interesting packages, and (c) we present a crowd
study that evaluates the sensitivity of real users to different kinds of
constraints and demonstrates that query relaxation is a powerful tool in
diversifying package recommendations
Lermontov crater on Mercury: Geology, morphology and spectral properties of the coexisting hollows and pyroclastic deposits
Abstract We present a multidisciplinary analysis of Lermontov crater, located at 15.24°N, −48.94°E in the Kuiper quadrangle of Mercury. By means of MESSENGER multiband MDIS-WAC and monochrome MDIS-NAC images, we prepare a high-resolution geological map of the crater and its closest surroundings, highlighting the presence of coexisting hollows and pyroclastic deposits on its floor. On the photometrically corrected MDIS-WAC multiband dataset, we apply an unsupervised clustering technique that spectrally separates the different materials located both inside and outside Lermontov crater. We observe that the pyroclastic deposits located on the crater's floor have a steep, red spectral behaviour dominated by the presence of a mixture of various pyroxenes containing Ti and Ni. On the contrary, the vents' rims are characterised by several hollows whose spectral slope is bluer than that of the pyroclastic deposits. By comparing the vent hollows to the hollows located farther out on the crater floor, we observe a steeper 0.62–0.82 μm spectral trend for those within the vents. The vent hollows' spectrum is more similar to the pyroclastic one in the above mentioned wavelength range. In addition, the vent hollows 0.55 μm absorption band could be related to CaS, while the small differences in slope at 0.48 μm and 0.62 μm could be due to the presence of other volatiles compounds, such as MgS or chlorides. When compared to hollows located in other hermean geological settings, Lermontov hollows are characterised by steeper spectra. This supports the interpretation that when hollows form, their bright deposits do not completely overwrite the spectral signature of the surrounding terrain, and their spectroscopic appearance is mixed with the composition of the terrain where they form
Paediatric recurrent pericarditis: Appropriateness of the standard of care and response to IL1-blockade
Objective: To analyse, in a cohort of paediatric patients with recurrent pericarditis (RP) undergoing anti-IL-1 treatment: the agent and dosing used as first line treatment, the long-term efficacy of IL1-blockers, the percentage of patients achieving a drug-free remission, the presence of variables associated with drug-free remission. Study design: Data were collected from patients' charts. Annualized relapse rate (ARR) was used for evaluation of treatment efficacy, bivariate logistic regression analysis for variables associated with drug-free remisison. Results: 58 patients, treated between 2008 and 2018, were included in the study (mean follow-up 2.6 years). 14/56 patients non-responsive to first line drugs were under-dosed. 57 patients were treated with anakinra: the ARR before and during daily treatment was 3.05 and 0.28, respectively (p<0.0001); an increase to 0.83 was observed after the reduction/withdrawal of treatment (p<.0001). The switch from anakinra to canakinumab (5 patients) was associated to an increase of the ARR (0.49 vs 1.46), but without statistical significance (p=0.215). At last follow-up only 9/58 patients had withdrawn all treatments. With the limits of a retrospective study and the heterogeneity between the patients enrolled in the study, a shorter duration of treatment with anakinra was the only variable associated with drug-free remission. Conclusion: This study shows that most of the pediatric patients with RP needing IL-1 blockade received an inadequate treatment with first line agents. The effectiveness of anakinra is supported by this study, but few patients achieved drug free-remission. The different rate of response to anakinra and canakinumab may suggest a possible role of IL1α in the pathogenesis of RP
Supermassive Black Holes in Galactic Nuclei: Past, Present and Future Research
This review discusses the current status of supermassive black hole research,
as seen from a purely observational standpoint. Since the early '90s, rapid
technological advances, most notably the launch of the Hubble Space Telescope,
the commissioning of the VLBA and improvements in near-infrared speckle imaging
techniques, have not only given us incontrovertible proof of the existence of
supermassive black holes, but have unveiled fundamental connections between the
mass of the central singularity and the global properties of the host galaxy.
It is thanks to these observations that we are now, for the first time, in a
position to understand the origin, evolution and cosmic relevance of these
fascinating objects.Comment: Invited Review, 114 pages. Because of space requirements, this
version contains low resolution figures. The full resolution version can be
downloaded from http://www.physics.rutgers.edu/~lff/publications.htm
Beta-Blocker Use in Older Hospitalized Patients Affected by Heart Failure and Chronic Obstructive Pulmonary Disease: An Italian Survey From the REPOSI Register
Beta (β)-blockers (BB) are useful in reducing morbidity and mortality in patients with heart failure (HF) and concomitant chronic obstructive pulmonary disease (COPD). Nevertheless, the use of BBs could induce bronchoconstriction due to β2-blockade. For this reason, both the ESC and GOLD guidelines strongly suggest the use of selective β1-BB in patients with HF and COPD. However, low adherence to guidelines was observed in multiple clinical settings. The aim of the study was to investigate the BBs use in older patients affected by HF and COPD, recorded in the REPOSI register. Of 942 patients affected by HF, 47.1% were treated with BBs. The use of BBs was significantly lower in patients with HF and COPD than in patients affected by HF alone, both at admission and at discharge (admission, 36.9% vs. 51.3%; discharge, 38.0% vs. 51.7%). In addition, no further BB users were found at discharge. The probability to being treated with a BB was significantly lower in patients with HF also affected by COPD (adj. OR, 95% CI: 0.50, 0.37-0.67), while the diagnosis of COPD was not associated with the choice of selective β1-BB (adj. OR, 95% CI: 1.33, 0.76-2.34). Despite clear recommendations by clinical guidelines, a significant underuse of BBs was also observed after hospital discharge. In COPD affected patients, physicians unreasonably reject BBs use, rather than choosing a β1-BB. The expected improvement of the BB prescriptions after hospitalization was not observed. A multidisciplinary approach among hospital physicians, general practitioners, and pharmacologists should be carried out for better drug management and adherence to guideline recommendations
Prescription appropriateness of anti-diabetes drugs in elderly patients hospitalized in a clinical setting: evidence from the REPOSI Register
Diabetes is an increasing global health burden with the highest prevalence (24.0%) observed in elderly people. Older diabetic adults have a greater risk of hospitalization and several geriatric syndromes than older nondiabetic adults. For these conditions, special care is required in prescribing therapies including anti- diabetes drugs. Aim of this study was to evaluate the appropriateness and the adherence to safety recommendations in the prescriptions of glucose-lowering drugs in hospitalized elderly patients with diabetes. Data for this cross-sectional study were obtained from the REgistro POliterapie-Società Italiana Medicina Interna (REPOSI) that collected clinical information on patients aged ≥ 65 years acutely admitted to Italian internal medicine and geriatric non-intensive care units (ICU) from 2010 up to 2019. Prescription appropriateness was assessed according to the 2019 AGS Beers Criteria and anti-diabetes drug data sheets.Among 5349 patients, 1624 (30.3%) had diagnosis of type 2 diabetes. At admission, 37.7% of diabetic patients received treatment with metformin, 37.3% insulin therapy, 16.4% sulfonylureas, and 11.4% glinides. Surprisingly, only 3.1% of diabetic patients were treated with new classes of anti- diabetes drugs. According to prescription criteria, at admission 15.4% of patients treated with metformin and 2.6% with sulfonylureas received inappropriately these treatments. At discharge, the inappropriateness of metformin therapy decreased (10.2%, P < 0.0001). According to Beers criteria, the inappropriate prescriptions of sulfonylureas raised to 29% both at admission and at discharge. This study shows a poor adherence to current guidelines on diabetes management in hospitalized elderly people with a high prevalence of inappropriate use of sulfonylureas according to the Beers criteria
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