GOT FIGURES? You can insert a figure in your article by clicking on the Insert Figure button, or dragging and dropping it anywhere onto the article. The Attach button below the figure lets you add data to your figures: a CSV, TSV, JSON file, an IPython Notebook (image below) or a d3.js interactive graphic (second image below, click on it and play with it!).

MLT These notes are mostly inspired from reading Cox & Giuli (“Principles of stellar structure”); some insights are from A.Maeder (“Physics, formation and evolution of rotating stars”) and Kippenhahn & Weigert (“Stellar Structure and Evolution”) Pressure Scale Height In hydrostatic equilibrium we can define the total pressure scale height, $\hp$, as -{\D r} \equiv {\hp} = {\p} where $\p$ is the total pressure ($ + $). The pressure scale height is a measure of the distance over which the pressure changes by an appreciable fraction of itself.

It has recently been proposed (Goodman et al. 2014) that long, skinny, infrared dark clouds may trace out the densest features of the Milky Way, which include spiral arms, and possible inter-arm tendrils. The features are so long and skinny that they are almost certainly caused and maintained by a global gravitational potential, so they are not likely to be self-gravitating molecular clouds. These “Bones of the Milky Way” could be used to help piece together the structure of the Galaxy, shedding light on age-old questions, such as the number of spiral arms in our Galaxy and their locations. We have searched for and identified a handful of candidate Bones: long, filamentary infrared-dark clouds found in position-velocity space where our current model of the Galaxy predicts spiral arms should lie. Utilizing archival data, we have confirmed the location of these Bone candidates in the Galactic mid-plane and within 5 km/s of a spiral arm. We propose to use the IRAM 30-m to create the first ever high-resolution CO map (1mm) of a candidate “Bone of the Milky Way,” simultaneously with a suite of dense gas tracers at 3mm with IRAM. Capitalizing on IRAM’s unique ability to map CO over large areas at high angular resolution while simultaneously obtaining kinematic information about the dense gas, we will provide the first measure of structure and kinematics toward these unique Galactic structures. Our total time request is XX hours to map XX sq. arcminutes at 1mm (¹³CO and C¹⁸O 2-1) and 3mm (HCO+, HCN 1-0, etc.) toward our most promising Northern-hemisphere candidate Bone, “BC1.”

Real-space grids are a powerful alternative for the simulation of electronic systems. One of the main advantages of the approach is the flexibility and simplicity of working directly in real space where the different fields are discretized on a grid, combined with competitive numerical performance and great potential for parallelization. These properties constitute a great advantage at the time of implementing and testing new physical models. Based on our experience with the Octopus code, in this article we discuss how the real-space approach has allowed for the recent development of new ideas for the simulation of electronic systems. Among these applications are approaches to calculate response properties, modeling of photoemission, optimal control of quantum systems, simulation of plasmonic systems, and the exact solution of the Schrödinger equation for low-dimensionality systems.

This vignette introduces the LBFGS package for R, which consists of a wrapper built around the libLBFGS optimization library written by Naoaki Okazaki. The lbfgs package implements both the Limited-memory Broyden-Fletcher-Goldfarb-Shanno (L-BFGS) and the Orthant-Wise Quasi-Newton Limited-Memory (OWL-QN) optimization algorithms. The L-BFGS algorithm solves the problem of minimizing an objective, given its gradient, by iteratively computing approximations of the inverse Hessian matrix. The OWL-QN algorithm finds the optimum of an objective plus the L1-norm of the problem’s parameters, and can be used to train log-linear models with L1-regularization. The package offers a fast and memory-efficient implementation of these optimization routines, which is particularly suited for high-dimensional problems. The lbfgs package compares favorably with other optimization packages for R in microbenchmark tests.

COURSE DESCRIPTION Here is the _Course Catalog_ description of the course: CHEMISTRY 160. THE QUANTUM WORLD Catalog Number: 3420 ALÁN ASPURU-GUZIK Contact email: [email protected] _For Undergraduates and Graduates_ Half course (fall term). TU., TH., 11:30-1 PM Exam Group: 15 Many essential properties of atoms, molecules and materials stem from their quantum mechanical nature. In this course, we will focus on the quantum mechanical aspects of physical chemistry. The basic principles of quantum mechanics will be introduced in tandem with the chemical concepts covered. We will describe the quantum mechanics of molecular bonding, vibrations and rotations. The fundamentals of molecular spectroscopy and photophysics will be seen in the light of quantum mechanics. We will end the course by introducing what goes behind the sciences in quantum chemistry packages for calculating molecular electronic structure and molecular properties. This year, the course will employ online forums for student discussions and turning in homework assignments. Most of the materials for evaluation will be take-home team programming exercises written in interactive Python (iPython). There will be no final exam. Prerequisites: Applied Mathematics 21a and 21b, Mathematics 21a and 21b, or equivalent preparation in calculus and differential equations; Physical Sciences 1 or equivalent preparation in chemical bonding and fundamental principles; Physical Sciences 2 or Physics 11a, and Physical Sciences 3 or Physics 11b.

_A 5-minute video demonstration of this paper is available at this YouTube link._ PREAMBLE A variety of research on human cognition demonstrates that humans learn and communicate best when more than one processing system (e.g. visual, auditory, touch) is used. And, related research also shows that, no matter how technical the material, most humans also retain and process information best when they can put a narrative "story" to it. So, when considering the future of scholarly communication, we should be careful not to do blithely away with the linear narrative format that articles and books have followed for centuries: instead, we should enrich it. Much more than text is used to communicate in Science. Figures, which include images, diagrams, graphs, charts, and more, have enriched scholarly articles since the time of Galileo, and ever-growing volumes of data underpin most scientific papers. When scientists communicate face-to-face, as in talks or small discussions, these figures are often the focus of the conversation. In the best discussions, scientists have the ability to manipulate the figures, and to access underlying data, in real-time, so as to test out various what-if scenarios, and to explain findings more clearly. THIS SHORT ARTICLE EXPLAINS—AND SHOWS WITH DEMONSTRATIONS—HOW SCHOLARLY "PAPERS" CAN MORPH INTO LONG-LASTING RICH RECORDS OF SCIENTIFIC DISCOURSE, enriched with deep data and code linkages, interactive figures, audio, video, and commenting.

Imagine an event generating multiple innovations in medical research in one weekend. Imagine an event giving spreadsheet-limited laboratory researchers a taste of what computers can _really_ do. Imagine an event where the powers of coding and analysis are combined with powers of biology, genetics and medicine to convert dry or unobtainable data into ground-breaking medical insight. And imagine it all done in a spirit of frenzied teamwork and friendly competition. This is HealthHack, a 48 hour hackfest in which medical researchers nucleate teams of brilliant, creative people to solve the data-processing problems faced by real researchers and real clinicians. The weekend opens on Friday evening with the problem owners pitching their ideas, problem and proposed solution, to the assembled hackers, followed by an hour in which hackers can approach problem owners with their questions and seek additional details. Hackers then choose which problem they are going to work on, and the assembled teams plan their assault and commence work on their application. Apart from going home (presumably) to sleep, the event runs all weekend. Sunday 4pm is _down tools_, and the teams then present their prototypes to everyone, with prizes for first place, second place, and _spirit of HealthHack_. Below is a sampling of the teams and their creations:

This article presents a new method to compute matrices from numerical simulations based on the ideas of sparse sampling and compressed sensing. The method is useful for problems where the determination of the entries of a matrix constitutes the computational bottleneck. We apply this new method to an important problem in computational chemistry: the determination of molecular vibrations from electronic structure calculations, where our results show that the overall scaling of the procedure can be improved in some cases. Moreover, our method provides a general framework for bootstrapping cheap low-accuracy calculations in order to reduce the required number of expensive high-accuracy calculations, resulting in a significant 3\(\times\) speed-up in actual calculations.

In this splinter session, ten speakers presented results on solar and stellar activity and how the two fields are connected. This was followed by a lively discussion and supplemented by short, one-minute highlight talks. The talks presented new theoretical and observational results on mass accretion on the Sun, the activity rate of flare stars, the evolution of the stellar magentic field on time scales of a single cycle and over the lifetime of a star, and two different approaches to model the radial-velocity jitter in cool stars that is due to the granulation on the surface. Talks and discussion showed how much the interpretation of stellar activity data relies on the sun and how the large number of objects available in stellar studies can extend the parameter range of activity models.

Recently, argued that the very long, very thin infrared dark cloud “Nessie” lies directly in the Galactic midplane and runs along the Scutum-Centaurus arm in position-position-velocity (_p-p-v_) space as traced by lower density CO and higher density NH₃ gas. Nessie was presented as the first “bone” of the Milky Way, an extraordinarily long, thin, high-contrast filament that can be used to map our Galaxy’s ”skeleton.“ Here, we present evidence for additional bones in the Milky Way Galaxy, arguing that Nessie is not a curiosity but one of several filaments that could potentially trace Galactic structure. Our ten bone candidates are all long, filamentary, mid-infrared extinction features which lie parallel to, and no more than twenty parsecs from, the physical Galactic mid-plane. We use CO, N₂H+, HCO+ and NH₃ radial velocity data to establish the three-dimensional location of the candidates in _p-p-v_ space. Of the ten candidates, six also: have a projected aspect ratio of ≥50: 1; run along, or extremely close to, the Scutum-Centaurus arm in _p-p-v_ space; _and_ exhibit no abrupt shifts in velocity. Evidence suggests that these candidates are marking the locations of significant spiral features, with the bone called filament 5 (”BC_18.88-0.09") being a close analog to Nessie in the Northern Sky. As molecular spectral-line and extinction maps cover more of the sky at increasing resolution and sensitivity, we seek to find more bones in future studies, ultimately to create a global-fit to the Galaxy’s spiral arms by piecing together individual skeletal features.

What famous observatory is more important than any other, yet has no lens, and no mirror? Is it Claudius Ptolemy's at Alexandria in the 2nd century AD? Maybe Uraniborg or Stjerneborg built by Tycho Brahe using 1% of the GDP of Denmark in the the 16th century? Nope. The answer is a creation of the 20th century: the internet. The ever-growing wealth of astronomical data available freely online literally holds answers to the mysteries of the Universe. The WorldWide Telescope is the telescope that lets any of us view the Universe using the internet as our observatory, to puzzle out those mysteries. The WorldWide Telescope is a "Universe Information System" that runs online in a web browser, or in Windows, on almost any computer or tablet. It accesses the internet's amazing treasure-trove of online data to provide beautiful all-sky imagery at dozens of wavelengths, as well as detailed images of deep sky objects, and other astrophyscially important targets. In addition, it offers links to in-depth information about objects, through links to diverse databases including Wikipedia and NASA's Astrophysics Data System, which holds all of the professional Astronomical literature since the 1800's. Users of WorldWide Telescope (also known as WWT) can create, share, and experience "Tours" of the Sky and of a three-dimesional model of the known Universe by saving paths through the program recorded as if by a virtual camera. These Tours look like video with musical scores, narration, additional imagery, and hyperlinks but are dramatically different in that you can interact and explore deeper and go anywhere at any time or pick up right where you left off! Just imagine WWT as an interactive web-browser for the sky. A sky-browser of sorts. Oh, and it's free.

What famous observatory is more important than any other, yet has no lens, and no mirror? Is it Claudius Ptolemy's at Alexandria in the 2nd century AD? Maybe Uraniborg or Stjerneborg built by Tycho Brahe using 1% of the GDP of Denmark in the the 16th century? Nope. The answer is a creation of the 20th century: the internet. The ever-growing wealth of astronomical data available freely online literally holds answers to the mysteries of the Universe. The WorldWide Telescope is the telescope that lets any of us view the Universe using the internet as our observatory, to puzzle out those mysteries. The WorldWide Telescope is a "Universe Information System" that runs either online in a web browser, or in Windows, on almost any computer. It accesses the internet's amazing treasure-trove of online data to provide beautiful all-sky imagery at dozens of wavelengths, as well as detailed images of deep sky objects, and other astrophyscially important targets. In addition, it offers links to deeper information about objects, through links to diverse databases including Wikipedia and NASA's Astrophysics Data System, which holds all of the professional Astronomical literature since the 1800's. Users of WorldWide Telescope (also known as WWT) can create, share, and experience "Tours" of the Sky and of a three-dimesional model of the known Unvierse by saving special paths through the program. And those Tours can have musical scores, be narrated, conatin added imagery, and hyperlinks. Just imagine WWT as a web-browser for the sky. A sky-browser of sorts. Oh, and it's free.

The abstract goes here

The abstract goes here

In the last portion of _Sidereus Nuncius_, Galileo reported his discovery of FOUR OBJECTS that appeared to form a straight line of stars near JUPITER. The first night, he witnessed a line of three little stars close to Jupiter parallel to the ecliptic; the following nights brought different arrangements and another star into his view, totaling four stars around Jupiter. Throughout the text, Galileo gave illustrations of the relative positions of Jupiter and its apparent companion stars as they appeared nightly from late January through early March 1610. The fact that they changed their positions relative to Jupiter from night to night, but always appeared in the same straight line near Jupiter, brought Galileo to deduce that they were four bodies in orbit around Jupiter. On January 11 after 4 nights of observation he wrote: “I therefore concluded and decided unhesitatingly, that there are three stars in the heavens moving about Jupiter, as Venus and Mercury round the Sun; which at length was established as clear as daylight by numerous subsequent observations. These observations also established that there are not only three, but four, erratic sidereal bodies performing their revolutions round Jupiter...the revolutions are so swift that an observer may generally get differences of position every hour.”

_This post accompanies a talk by the same name and author, presented at the 223rd Meeting of the American Astronomical Society, at 11:40 AM on January 6, 2014. Talk slides will be online after noon on January 6 at http://projects.iq.harvard.edu/seamlessastronomy/presentations._ ABSTRACT In 1610, when Galileo pointed his small telescope at Jupiter, he drew sketches to record what he saw. After just a few nights of observing, he understood his sketches to be showing moons orbiting Jupiter. It was the visualization of Galileo's observations that led to his understanding of a clearly Sun-centered solar system, and to the revolution this understanding then caused. Similar stories can be found throughout the history of Astronomy, but visualization has never been so essential as it is today, when we find ourselves blessed with a larger wealth and diversity of data, per astronomer, than ever in the past. In this talk, I will focus on how modern tools for interactive “linked-view” visualization can be used to gain insight. Linked views, which dynamically update all open graphical displays of a data set (e.g. multiple graphs, tables and/or images) in response to user selection, are particularly important in dealing with so-called “high-dimensional data.” These dimensions need not be spatial, even though, e.g. in the case of radio spectral-line cubes or optical IFU data), they often are. Instead, “dimensions” should be thought of as any measured attribute of an observation or a simulation (e.g. time, intensity, velocity, temperature, etc.). The best linked-view visualization tools allow users to explore relationships amongst all the dimensions of their data, and to weave statistical and algorithmic approaches into the visualization process in real time. Particular tools and services will be highlighted in this talk, including: Glue (glueviz.org), the ADS All Sky Survey (adsass.org), WorldWide Telescope (worldwidetelescope.org), yt (yt-project.org), d3po (d3po.org), and a host of tools that can be interconnected via the SAMP message-passing architecture. The talk will conclude with a discussion of future challenges, including the need to educate astronomers about the value of visualization and its relationship to astrostatistics, and the need for new technologies to enable humans to interact more effectively with large, high-dimensional data sets.

This is a collection of undergrad-level order-of-magnitude problems and their solutions