Dynamic Poisson Factorization

Models for recommender systems use latent factors to explain the preferences and behaviors of users with respect to a set of items (e.g., movies, books, academic papers). Typically, the latent factors are assumed to be static and, given these factors, the observed preferences and behaviors of users are assumed to be generated without order. These assumptions limit the explorative and predictive capabilities of such models, since users' interests and item popularity may evolve over time. To address this, we propose dPF, a dynamic matrix factorization model based on the recent Poisson factorization model for recommendations. dPF models the time evolving latent factors with a Kalman filter and the actions with Poisson distributions. We derive a scalable variational inference algorithm to infer the latent factors. Finally, we demonstrate dPF on 10 years of user click data from arXiv.org, one of the largest repository of scientific papers and a formidable source of information about the behavior of scientists. Empirically we show performance improvement over both static and, more recently proposed, dynamic recommendation models. We also provide a thorough exploration of the inferred posteriors over the latent variables.Comment: RecSys 201

Modeling the planar rocking of a rigid body with irregular geometry

The nonlinear dynamics of rocking rigid bodies with simple geometries, such as rectangular blocks and cylinders, have been the focus of the rocking community over the last six decades. However, many objects that are prone to rocking or overturning do not conform to such geometries. These objects include museum artifacts and precariously balanced rocks in the natural world. Even in cases where the response of the rocking body is planar, the geometry of the body is much more complicated than the commonly studied geometry of a rocking block or a body with only two rocking corners. This paper introduces a complete model that can examine the planar motion of a body with an irregular in-plane polygonal geometry when subjected to a vibrational excitation, utilizing the geometry of the body as an input—for example, in the form of a stereolithography (STL) file. The model is used for studying the rocking response of an object while taking into account sliding and free flight. The problem is formulated and solved using Newtonian equations of motion, and impacts are treated as hard. A robust framework for integrating the occurring discontinuous equations of motion and for detecting transitions between patterns of motion and impacts, using MATLAB, is presented. Suitably chosen examples demonstrate the importance of accounting for the actual geometry of the studied rocking body, whose dynamic response is substantially richer than an object with simplified geometry

Feline leishmaniosis due to Leishmania infantum (syn. L. chagasi)

Από τις αρχές του 20ου αιώνα έχουν καταγραφεί, σε διάφορες περιοχές, περιστατικά φυσικής μόλυνσης τηςγάτας από οκτώ τουλάχιστον είδη του γένους Leishmania. Για τις μεσογειακές χώρες, ιδιαίτερο ενδιαφέρον έχει η μόλυνσηαπό την L. infantum, που είναι το αίτιο της λεϊσμανίωσης του σκύλου και της σπλαγχνικής ή δερματικής λεϊσμανίασης τουανθρώπου και για τις οποίες η γάτα θα μπορούσε να αποτελεί «δευτερογενή δεξαμενή» του παρασίτου. Αν και το ποσοστότων μολυσμένων γατών μπορεί, σε ορισμένες περιπτώσεις, να ξεπερνά ακόμη και το 60%, τα συμπτωματικά ζώα είναι σπάνια,επειδή η γάτα είναι ανθεκτικότερη στη λεϊσμανίωση σε σύγκριση με το σκύλο. Οι μολυσμένες, όμως, γάτες ενδέχεται ναεμφανίσουν δερματικές και οφθαλμικές αλλοιώσεις ή/και συμπτώματα από διάφορα εσωτερικά όργανα. Τα έλκη και τα οζίδιαπου εντοπίζονται κατά κύριο λόγο στα βλεννογονοδερματικά όρια, το επιρρίνιο, το πρόσωπο και τα πτερύγια των αυτιώνείναι οι δερματικές εκείνες αλλοιώσεις που εμφανίζονται συχνότερα στην πράξη. Λιγότερο συχνές είναι η αποφολιδωτικήδερματίτιδα και η ποδοδερματίτιδα, ενώ άγνωστο παραμένει εάν για τις βλατίδες, τις εφελκίδες και την αλωπεκία, που έχουνπαρατηρηθεί σε ορισμένα μολυσμένα ζώα, θα μπορούσε πράγματι να ενοχοποιηθεί η λεϊσμανίωση. Στις οφθαλμικές αλλοιώσειςπεριλαμβάνονται η επιπεφυκίτιδα, η (ελκώδης) κερατίτιδα, η πρόσθια και οπίσθια ραγοειδίτιδα, η χοριοαμφιβληστροειδίτιδακαι η πανοφθαλμίτιδα. Από τα συμπτώματα και τις παθολογικές καταστάσεις από τα εσωτερικά όργανα, τα μόνα που θαμπορούσαν να αποδοθούν στη λεϊσμανίωση της γάτας είναι η περιφερική λεμφαδενομεγαλία, η σπληνομεγαλία, η ηπατομεγαλίακαι η νεφρίτιδα που ενδέχεται να οδηγήσει σε χρόνια νεφρική ανεπάρκεια. Από τα εργαστηριακά ευρήματα, το πλέον χαρακτηριστικόείναι η υπερσφαιριναιμία που συνήθως είναι πολυκλωνική και σπανιότερα μονοκλωνική. Η λεϊσμανίωση της γάταςσυχνά συνυπάρχει με πολλά άλλα νοσήματα και παθήσεις, που θα μπορούσαν να μεταβάλουν την κλινική εικόνα και ενδεχομένωςνα καταστείλουν το ανοσοποιητικό σύστημα των μολυσμένων ζώων. Όπως και στο σκύλο, η διάγνωση της λεϊσμανίωσης στηγάτα στηρίζεται στην αλυσιδωτή αντίδραση της πολυμεράσης (PCR), την κυτταρολογική, ιστοπαθολογική και ανοσοϊστοχημικήεξέταση, την καλλιέργεια σε ειδικά υποστρώματα και τις ορολογικές εξετάσεις. Όλες οι παραπάνω διαγνωστικές μέθοδοιπαρουσιάζουν πλεονεκτήματα και μειονεκτήματα, ενώ η ευαισθησία τους ποικίλλει ανάλογα με το διαθέσιμο βιολογικό υλικόκαι την τεχνική που εφαρμόζεται κάθε φορά. Η κυτταρολογική, ιστοπαθολογική ή/και ανοσοϊστοχημική εξέταση από το μυελότων οστών, τα λεμφογάγγλια, τη σπλήνα, τις δερματικές και τις οφθαλμικές αλλοιώσεις στοχεύει στην ανίχνευση των αμαστιγοφόρων μορφών, που όταν βρεθούν, η μόλυνση αποδεικνύεται πέρα από κάθε αμφιβολία. Οι ορολογικές εξετάσεις, ανάλογαμε τη μεθοδολογία και το όριο διαχωρισμού, υποεκτιμούν ή υπερεκτιμούν την πραγματική συχνότητα της μόλυνσης σε γάτεςπου ζουν σε περιοχές στις οποίες η νόσος ενδημεί. Με την PCR, που ανιχνεύει το DNA του παρασίτου στο μυελό των οστών,τα λεμφογάγγλια, τη σπλήνα, το δέρμα και ενδεχομένως το περιφερικό αίμα, φαίνεται ότι εξυπηρετούνται καλύτερα οι επιζωοτιολογικες μελέτες. Μέχρι σήμερα η θεραπευτική αντιμετώπιση της λεϊσμανίωσης της γάτας στηρίζεται κυρίως στημακροχρόνια χορήγηση της αλλοπουρινόλης, σε συνδυασμό με τη θεραπεία των νοσημάτων και των παθήσεων που ενδεχομένωςσυνυπάρχουν.From the beginning of the 20th century, feline infections by at least eight different Leishmania species have been sporadically reported, worldwide. In the Mediterranean countries, feline infection imposed by L. infantum, the aetiological agent of canine leishmaniosis and human visceral and cutaneous leishmaniasis, is of particular importance, because cats may represent a "secondary reservoir" of the parasite in the nature. Although the prevalence of the infection may be as high as 60%, most infected cats are resistant and remain asymptomatic, while only occasionally, they may present cutaneous and/or ocular lesions, and perhaps systemic clinical signs. In feline leishmaniosis, ulcers and nodules, usually localized at mucocutaneous junctions, planum nasale, face and ear pinnae, constitute the mainstream of cutaneous lesions. In a small number of cases, exfoliative dermatitis and pododermatitis have been noted, whereas a cause-and-effect relationship, between feline leishmaniosis and the presence of papules, crusts and generalized alopecia remains speculative. Ocular lesions, such as those associated with conjunctivitis, (ulcerative) keratitis, posterior or anterior uveitis, chorioretinitis and panopthalmitis are relatively common. The only systemic signs that have been constantly associated with feline leishmaniosis are peripheral lymphadenomegaly, splenomegaly, hepatomegaly and chronic nephritis that may lead to chronic renal failure. The most consistent laboratory abnormality is hyperglobulinaemia that is usually polyclonal. Feline leishmaniosis can co-exist with various other infectious and non-infectious diseases that may alter its clinical picture and/or influence the immunological response of the infected cat. Diagnosis is usually based on the results of cytology,histopathology, immunohistochemistry, culture, serology and polymerase chain reaction (PCR). Apart from the advantages and limitations inherent to each of these methods, their diagnostic value depends on many factors, such as the biological sample being used, the reagents and the particular technique employed. Leishmania amastigotes can be detected by applying bone marrow, lymph node, spleen, cutaneous and ocular cytology, histopathology, and/or immunohistochemistry, which are 100% specific. Serology may underestimate or even overestimate the frequency of the infection in the endemic areas, depending on the methodology and the cut-off value, whereas PCR, that can be performed on the tissues mentioned before, plus the peripheral blood may be a better option for epidemiological studies. Although a uniformly effective treatment for symptomatic cats has not been established yet, long-term allopurinol administration, along with the management of any concurrent diseases, is the only treatment to suggest at moment

Sensitivity of preputial and vaginal exfoliative cytological examination for diagnosis of canine leishmaniosis (Leishmania infantum)

Σκοπός της μελέτης ήταν η εκτίμηση της ευαισθησίας της κυτταρολογικής εξέτασης από δείγματα από την ακροποσθία ή τον κόλπο για διάγνωση της λεϊσμανίωσης του σκύλου, καθώς προηγούμενες μελέτες έχουν δείξει την παρουσία αμαστιγωτών μορφών Leishmania infantum στο πέος και την ακροποσθία των αρσενικών, καθώς και στον κόλπο των θηλυκών σκύλων με λεϊσμανίωση. Η εξέταση αυτή θα μπορούσε να αντικαταστήσει την κυτταρολογική εξέταση των λεμφογαγγλίων, του σπλήνα και του μυελού των οστών που απαιτούν περισσότερο επεμβατική δειγματοληψία. Χρησιμοποιήθηκαν 20 αρσενικοί και 18 θηλυκοί σκύλοι με επιβεβαιωμένη λεϊσμανίωση. Από κάθε αρσενικό σκύλο εξετάστηκαν τρία κυτταρολογικά επιχρίσματα από υλικό από διαφορετικά σημεία της κοιλότητας της ακροποσθίας, ενώ από κάθε θηλυκό σκύλο εξετάστηκε ένα επίχρισμα από την πρόσθια μοίρα του κόλπου. Ύστερα από μικροσκοπική εξέταση σε μεγέθυνση 1.000× επί 20 min δεν διαπιστώθηκαν  αμαστιγωτές μορφές της Leishmania spp. σε κανένα από τα παραπάνω επιχρίσματα. Κατά συνέπεια, η κυτταρολογική εξέταση δειγμάτων από την ακροποσθία ή τον κόλπο δεν αποτελεί ευαίσθητη μέθοδο για τη διάγνωση της λεϊσμανίωσης του σκύλου.Aim of the study was to examine sensitivity of preputial and vaginal exfoliative cytological examination as a noninvasive alternative to lymph node, spleen and bone marrow cytology, for detection of Leishmania infantum amastigotes in dogs with leishmaniosis, as, in previous studies, the protozoa have been observed in the penis and prepuce of male dogs and in the vagina of female dogs with leishmaniosis. In total, 20 male  and 18 female dogs with confirmed leishmaniosis were included inthe study. Three cytology smears were prepared from different sites of the preputial cavity of males and one smear was prepared from the anterior vagina of females. Leishmania amastigotes were not observed in these samples after microscopic examination for 20 min at 1,000× magnification. Therefore, preputial and vaginal exfoliative cytology is not recommended for routine diagnosis of canine leishmaniosis

Early life inter-kingdom interactions shape the immunological environment of the airways

Background: There is increasing evidence that the airway microbiome plays a key role in the establishment of respiratory health by interacting with the developing immune system early in life. While it has become clear that bacteria are involved in this process, there is a knowledge gap concerning the role of fungi. Moreover, the inter-kingdom interactions that influence immune development remain unknown. In this prospective exploratory human study, we aimed to determine early post-natal microbial and immunological features of the upper airways in 121 healthy newborns. Results: We found that the oropharynx and nasal cavity represent distinct ecological niches for bacteria and fungi. Breastfeeding correlated with changes in microbiota composition of oropharyngeal samples with the greatest impact upon the relative abundance of Streptococcus species and Candida. Host transcriptome profiling revealed that genes with the highest expression variation were immunological in nature. Multi-omics factor analysis of host and microbial data revealed unique co-variation patterns. Conclusion: These data provide evidence of a diverse multi-kingdom microbiota linked with local immunological characteristics in the first week of life that could represent distinct trajectories for future respiratory health

Neural networks for cryptocurrency evaluation and price fluctuation forecasting

International audienceToday, there is a growing number of digital assets, often built on questionable technical foundations. We design and implement supervized learning models in order to explore different aspects of a cryptocurrency affecting its performance, its stability as well as its daily price fluctuation. One characteristic feature of our approach is that we aim at a holistic view that would integrate all available information: First, financial information, including market capitalization and historical daily prices. Second, features related to the underlying blockchain from blockchain explorers like network activity: blockchains handle the supply and demand of a cryptocurrency. Lastly, we integrate software development metrics based on GitHub activity by the supporting team. We set two goals. First, to classify a given cryptocurrency by its performance, where stability and price increase are the positive features. Second, to forecast daily price tendency through regression; this is of course a well-studied problem. A related third goal is to determine the most relevant features for such analysis. We compare various neural networks using most of the widely traded digital currencies (e.g. Bitcoin, Ethereum and Litecoin) in both classification and regression settings. Simple Feedforward neural networks are considered, as well as Recurrent neural networks (RNN) along with their improvements, namely Long Short-Term Memory and Gated Recurrent Units. The results of our comparative analysis indicate that RNNs provide the most promising results

Predicting lymphoma in Sjogren's syndrome and the pathogenetic role of parotid microenvironment through precise parotid swelling recording

Objective Parotid swelling (PSW) is a major predictor of non-Hodgkin's lymphoma (NHL) in primary SS (pSS). However, since detailed information on the time of onset and duration of PSW is scarce, this was investigated to verify whether it may lead to further improved prediction. NHL localization was concomitantly studied to evaluate the role of the parotid gland microenvironment in pSS-related lymphomagenesis. Methods A multicentre study was conducted among patients with pSS who developed B cell NHL during follow-up and matched controls that did not develop NHL. The study focused on the history of salivary gland and lachrymal gland swelling, evaluated in detail at different times and for different durations, and on the localization of NHL at onset. Results PSW was significantly more frequent among the cases: at the time of first referred pSS symptoms before diagnosis, at diagnosis and from pSS diagnosis to NHL. The duration of PSW was evaluated starting from pSS diagnosis, and the NHL risk increased from PSW of 2-12 months to >12 months. NHL was prevalently localized in the parotid glands of the cases. Conclusion A more precise clinical recording of PSW can improve lymphoma prediction in pSS. PSW as a very early symptom is a predictor, and a longer duration of PSW is associated with a higher risk of NHL. Since lymphoma usually localizes in the parotid glands, and not in the other salivary or lachrymal glands, the parotid microenvironment appears to be involved in the whole history of pSS and related lymphomagenesis

High-resolution 3D imaging uncovers organ-specific vascular control of tissue aging

Blood vessels provide supportive microenvironments for maintaining tissue functions. Age-associated vascular changes and their relation to tissue aging and pathology are poorly understood. Here, we perform 3D imaging of young and aging vascular beds. Multiple organs in mice and humans demonstrate an age-dependent decline in vessel density and pericyte numbers, while highly remodeling tissues such as skin preserve the vasculature. Vascular attrition precedes the appearance of cellular hallmarks of aging such as senescence. Endothelial VEGFR2 loss-of-function mice demonstrate that vascular perturbations are sufficient to stimulate cellular changes coupled with aging. Age-associated tissue-specific molecular changes in the endothelium drive vascular loss and dictate pericyte to fibroblast differentiation. Lineage tracing of perivascular cells with inducible PDGFRβ and NG2 Cre mouse lines demonstrated that increased pericyte to fibroblast differentiation distinguishes injury-induced organ fibrosis and zymosan-induced arthritis. To spur further discoveries, we provide a freely available resource with 3D vascular and tissue maps