Bayesian Uncertainty for Gradient Aggregation in Multi-Task Learning

As machine learning becomes more prominent there is a growing demand to perform several inference tasks in parallel. Running a dedicated model for each task is computationally expensive and therefore there is a great interest in multi-task learning (MTL). MTL aims at learning a single model that solves several tasks efficiently. Optimizing MTL models is often achieved by computing a single gradient per task and aggregating them for obtaining a combined update direction. However, these approaches do not consider an important aspect, the sensitivity in the gradient dimensions. Here, we introduce a novel gradient aggregation approach using Bayesian inference. We place a probability distribution over the task-specific parameters, which in turn induce a distribution over the gradients of the tasks. This additional valuable information allows us to quantify the uncertainty in each of the gradients dimensions, which can then be factored in when aggregating them. We empirically demonstrate the benefits of our approach in a variety of datasets, achieving state-of-the-art performance

Supernova PTF12glz: a possible shock breakout driven through an aspherical wind

We present visible-light and ultraviolet (UV) observations of the supernova PTF12glz. The SN was discovered and monitored in near-UV and R bands as part of a joint GALEX and Palomar Transient Factory campaign. It is among the most energetic Type IIn supernovae observed to date (~10^51erg). If the radiated energy mainly came from the thermalization of the shock kinetic energy, we show that PTF12glz was surrounded by ~1 solar mass of circumstellar material (CSM) prior to its explosive death. PTF12glz shows a puzzling peculiarity: at early times, while the freely expanding ejecta are presumably masked by the optically thick CSM, the radius of the blackbody that best fits the observations grows at ~8000km/s. Such a velocity is characteristic of fast moving ejecta rather than optically thick CSM. This phase of radial expansion takes place before any spectroscopic signature of expanding ejecta appears in the spectrum and while both the spectroscopic data and the bolometric luminosity seem to indicate that the CSM is optically thick. We propose a geometrical solution to this puzzle, involving an aspherical structure of the CSM around PTF12glz. By modeling radiative diffusion through a slab of CSM, we show that an aspherical geometry of the CSM can result in a growing effective radius. This simple model also allows us to recover the decreasing blackbody temperature of PTF12glz. SLAB-Diffusion, the code we wrote to model the radiative diffusion of photons through a slab of CSM and evaluate the observed radius and temperature, is made available on-line.Comment: Sumbitted to ApJ. Comments are welcom

Risk Factors for the Development of Neurological Deficits in Metastatic Spinal Disease: An International, Multicenter Delphi Study

Study designDelphi study.ObjectiveThe objective of this study was to identify risk factors associated with the development and/or progression of neurological deficits in patients with metastatic spinal disease.MethodsA three-round Delphi study was conducted between January-May 2023 including AO Spine members, comprising mainly neurosurgeons and orthopedic surgeons. In round 1, participants listed radiological factors, patient characteristics, tumor characteristics, previous cancer-related treatment factors and additional factors. In round 2, participants ranked the factors on importance per category and selected a top 9 from all factors. Kendall's W coefficient of concordance was calculated as a measure of consensus. In the final round, participants provided feedback on the rankings resulting from round 2. Lastly, the highest-ranking factors were more clearly defined and operationalized by an expert panel.ResultsOver two hundred physicians and researchers participated in each round. The factors listed in the first round were collapsed into 12 radiological factors, 14 patient characteristics, 6 tumor characteristics and 12 previous cancer-related treatment factors. High agreement was found in round 3 on the top-half lists in each category and the overall top 9, originating from round 2. Kendall's W indicated strong agreement between the participants. 'Epidural spinal cord compression', 'aggressive tumor behavior' and 'mechanical instability' were deemed most influential for the development of neurological deficits.ConclusionThis study provides factors that may be related to the development and/or progression of neurological deficits in patients with metastatic spinal disease. This list can serve as a basis for future directions in prognostication research

Identification of novel mutations in X-linked retinitis pigmentosa families and implications for diagnostic testing

Contains fulltext : 69886.pdf (publisher's version ) (Open Access)PURPOSE: The goal of this study was to identify mutations in X-chromosomal genes associated with retinitis pigmentosa (RP) in patients from Germany, The Netherlands, Denmark, and Switzerland. METHODS: In addition to all coding exons of RP2, exons 1 through 15, 9a, ORF15, 15a and 15b of RPGR were screened for mutations. PCR products were amplified from genomic DNA extracted from blood samples and analyzed by direct sequencing. In one family with apparently dominant inheritance of RP, linkage analysis identified an interval on the X chromosome containing RPGR, and mutation screening revealed a pathogenic variant in this gene. Patients of this family were examined clinically and by X-inactivation studies. RESULTS: This study included 141 RP families with possible X-chromosomal inheritance. In total, we identified 46 families with pathogenic sequence alterations in RPGR and RP2, of which 17 mutations have not been described previously. Two of the novel mutations represent the most 3'-terminal pathogenic sequence variants in RPGR and RP2 reported to date. In exon ORF15 of RPGR, we found eight novel and 14 known mutations. All lead to a disruption of open reading frame. Of the families with suggested X-chromosomal inheritance, 35% showed mutations in ORF15. In addition, we found five novel mutations in other exons of RPGR and four in RP2. Deletions in ORF15 of RPGR were identified in three families in which female carriers showed variable manifestation of the phenotype. Furthermore, an ORF15 mutation was found in an RP patient who additionally carries a 6.4 kbp deletion downstream of the coding region of exon ORF15. We did not identify mutations in 39 sporadic male cases from Switzerland. CONCLUSIONS: RPGR mutations were confirmed to be the most frequent cause of RP in families with an X-chromosomal inheritance pattern. We propose a screening strategy to provide molecular diagnostics in these families

The scientific payload of the Ultraviolet Transient Astronomy Satellite (ULTRASAT)

The Ultraviolet Transient Astronomy Satellite (ULTRASAT) is a space-borne near UV telescope with an unprecedented large field of view (200 sq. deg.). The mission, led by the Weizmann Institute of Science and the Israel Space Agency in collaboration with DESY (Helmholtz association, Germany) and NASA (USA), is fully funded and expected to be launched to a geostationary transfer orbit in Q2/3 of 2025. With a grasp 300 times larger than GALEX, the most sensitive UV satellite to date, ULTRASAT will revolutionize our understanding of the hot transient universe, as well as of flaring galactic sources. We describe the mission payload, the optical design and the choice of materials allowing us to achieve a point spread function of ~10arcsec across the FoV, and the detector assembly. We detail the mitigation techniques implemented to suppress out-of-band flux and reduce stray light, detector properties including measured quantum efficiency of scout (prototype) detectors, and expected performance (limiting magnitude) for various objects.Comment: Presented in the SPIE Astronomical Telescopes + Instrumentation 202

Risk Factors for the Development of Neurological Deficits in Metastatic Spinal Disease: An International, Multicenter Delphi Study

Study Design: Delphi study Objective: The objective of this study was to identify risk factors associated with the development and/or progression of neurological deficits in patients with metastatic spinal disease. Methods: A three-round Delphi study was conducted between January-May 2023 including AO Spine members, comprising mainly neurosurgeons and orthopedic surgeons. In round 1, participants listed radiological factors, patient characteristics, tumor characteristics, previous cancer-related treatment factors and additional factors. In round 2, participants ranked the factors on importance per category and selected a top 9 from all factors. Kendall’s W coefficient of concordance was calculated as a measure of consensus. In the final round, participants provided feedback on the rankings resulting from round 2. Lastly, the highest-ranking factors were more clearly defined and operationalized by an expert panel. Results: Over two hundred physicians and researchers participated in each round. The factors listed in the first round were collapsed into 12 radiological factors, 14 patient characteristics, 6 tumor characteristics and 12 previous cancer-related treatment factors. High agreement was found in round 3 on the top-half lists in each category and the overall top 9, originating from round 2. Kendall’s W indicated strong agreement between the participants. ‘Epidural spinal cord compression’, ‘aggressive tumor behavior’ and ‘mechanical instability’ were deemed most influential for the development of neurological deficits. Conclusion: This study provides factors that may be related to the development and/or progression of neurological deficits in patients with metastatic spinal disease. This list can serve as a basis for future directions in prognostication research