Fitting the integrated Spectral Energy Distributions of Galaxies

Fitting the spectral energy distributions (SEDs) of galaxies is an almost universally used technique that has matured significantly in the last decade. Model predictions and fitting procedures have improved significantly over this time, attempting to keep up with the vastly increased volume and quality of available data. We review here the field of SED fitting, describing the modelling of ultraviolet to infrared galaxy SEDs, the creation of multiwavelength data sets, and the methods used to fit model SEDs to observed galaxy data sets. We touch upon the achievements and challenges in the major ingredients of SED fitting, with a special emphasis on describing the interplay between the quality of the available data, the quality of the available models, and the best fitting technique to use in order to obtain a realistic measurement as well as realistic uncertainties. We conclude that SED fitting can be used effectively to derive a range of physical properties of galaxies, such as redshift, stellar masses, star formation rates, dust masses, and metallicities, with care taken not to over-interpret the available data. Yet there still exist many issues such as estimating the age of the oldest stars in a galaxy, finer details ofdust properties and dust-star geometry, and the influences of poorly understood, luminous stellar types and phases. The challenge for the coming years will be to improve both the models and the observational data sets to resolve these uncertainties. The present review will be made available on an interactive, moderated web page (sedfitting.org), where the community can access and change the text. The intention is to expand the text and keep it up to date over the coming years.Comment: 54 pages, 26 figures, Accepted for publication in Astrophysics & Space Scienc

On Stability in Competition: Tying and Horizontal Product Differentiation

We combine Hotelling’s model of product differentiation with tie-in sales. A monopolist in one market competes with another firm in a second market. In equilibrium firms choose zero product differentiation. Due to the tying structure no firm can gain the whole market by a small price reduction. A differentiation effect due to tie-in sales leads to this equilibrium stability. Copyright Springer Science+Business Media, LLC 2007Horizontal product differentiation, Hotelling, Tie-in sales, Equilibrium existence, D43, L10, L11, L13,

Migraine

Migraine is a common headache disorder. This Primer by Ferrari and colleagues summarizes the epidemiology, pathophysiology, diagnosis and treatment of migraine. Moreover, quality of life issues faced by patients with migraine and future research avenues are discussed.Migraine is a common, chronic, disorder that is typically characterized by recurrent disabling attacks of headache and accompanying symptoms, including aura. The aetiology is multifactorial with rare monogenic variants. Depression, epilepsy, stroke and myocardial infarction are comorbid diseases. Spreading depolarization probably causes aura and possibly also triggers trigeminal sensory activation, the underlying mechanism for the headache. Despite earlier beliefs, vasodilation is only a secondary phenomenon and vasoconstriction is not essential for antimigraine efficacy. Management includes analgesics or NSAIDs for mild attacks, and, for moderate or severe attacks, triptans or 5HT(1B/1D) receptor agonists. Because of cardiovascular safety concerns, unreliable efficacy and tolerability issues, use of ergots to abort attacks has nearly vanished in most countries. CGRP receptor antagonists (gepants) and lasmiditan, a selective 5HT1(F) receptor agonist, have emerged as effective acute treatments. Intramuscular onabotulinumtoxinA may be helpful in chronic migraine (migraine on >= 15 days per month) and monoclonal antibodies targeting CGRP or its receptor, as well as two gepants, have proven effective and well tolerated for the preventive treatment of migraine. Several neuromodulation modalities have been approved for acute and/or preventive migraine treatment. The emergence of new treatment targets and therapies illustrates the bright future for migraine management.Paroxysmal Cerebral Disorder

Automatically assessing graph-based diagrams

To date there has been very little work on the machine understanding of imprecise diagrams, such as diagrams drawn by students in response to assessment questions. Imprecise diagrams exhibit faults such as missing, extraneous and incorrectly formed elements. The semantics of imprecise diagrams are difficult to determine. While there have been successful attempts at assessing text (essays) automatically, little success with diagrams has been reported. In this paper, we explain an approach to the automatic interpretation of graph-based diagrams based on a five-stage framework. The paper describes our approach to automatically grading graph-based diagrams and reports on some experiments into the automatic grading of student diagrams. The diagrams were produced under examination conditions and the output of the automatic marker was compared with the original human marks across a large number of diagrams. The experiments show good agreement between the performance of the automatic marker and the human markers. The paper also describes how the automatic marking algorithm has been incorporated into a variety of software teaching and learning tools. One tool supports the human grading of entity-relationship diagrams (ERDs). Another tool is for student use during the revision of ERDs. This tool automatically marks student answers in real-time and provides dynamically created feedback to help guide the student's progress