class: center, middle, inverse, title-slide # Lecture 1 ## Intro, math and micro review ### Ivan Rudik ### AEM 6510 --- exclude: true ```r if (!require("pacman")) install.packages("pacman") ``` ``` ## Loading required package: pacman ``` ```r pacman::p_load( tidyverse, tidylog, xaringanExtra, Ryacas, rlang ) options(htmltools.dir.version = FALSE) knitr::opts_hooks$set(fig.callout = function(options) { if (options$fig.callout) { options$echo <- FALSE } knitr::opts_chunk$set(echo = TRUE, fig.align="center") options }) ``` <style type="text/css"> /* custom.css */ .left-code { color: #777; width: 38%; height: 92%; float: left; } .right-plot { width: 60%; float: right; padding-left: 1%; } .plot-callout { height: 225px; width: 450px; bottom: 5%; right: 5%; position: absolute; padding: 0px; z-index: 100; } .plot-callout img { width: 100%; border: 4px solid #23373B; } </style> --- # AEM 6510: Environmental and resource economics .hi-blue[Welcome to AEM 6510] -- **Synchronous class time:** Tuesday and Thursday 3:00-4:15 **Instructor:** Ivan Rudik **Zoom office hours:** Tuesday and Thursday 4:20-4:50 **Teaching assistant:** Diego Cardoso **TA zoom office hours:** Monday 3:00-4:00 Class and office hour zoom links are on Canvas --- # AEM 6510: Environmental and resource economics **Textbooks:** - A Course in Environmental Economics by Phaneuf and Requate - [Causal Inference: The Mixtape](https://www.scunning.com/mixtape.html) by Cunningham **Formal Prerequisites:** MATH 1110 or equivalent. **Highly recommended:** Intermediate micro and masters-level econometrics **Lecture notes:** https://github.com/irudik/aem6510, accessible through Canvas --- # Zoom etiquette A few requests on how you should interact through zoom: 1. Be on time 2. Stay muted unless answering/asking a question 3. Turn on video, have a non-distracting actual or virtual background 4. Display your full name and any preferred nick name 5. Be active! - Ask questions in chat or use the hand raise feature - If I don't respond in a reasonable timeframe feel free to unmute and ask your question --- # What's the point of the course? To learn: Core environmental theory -- Theory of regulation -- Applied welfare analysis -- How to do empirical analysis on the environment -- How to use R and do geospatial analysis - This is increasingly important in environmental economics --- # What do you need to succeed in this class? Attend lectures if possible -- Do your homework and prelims -- Start your final project early -- Contact me or Diego if you have and questions or concerns --- # Here's how you'll be graded Prelims (2): 30% and 25% (one theory, one empirical) Problem sets (4): 20% Literature review paper: 20% Literature review presentation: 5% A: 92-100; A-: 90-91 B+: 88-89; B: 82-87; B-: 80-81 C+: 78-79; C: 72-77; C-: 70-71 D+: 68-69; D: 62-67; D-: 60-61 F: < 60 --- # Prelims There are two, one on theory and one on empirical methods -- Your highest-scoring prelim is 30% of your grade, your lowest-scoring prelim is 25% -- Prelims will basically just be longer homeworks that you are expected to complete .hi-red[on your own] -- You have 24 hours to finish the theory prelim and 48 hours to finish the empirical prelim -- Late prelims automatically get 30% deducted: don't wait until the last minute to turn them in --- # Problem sets There will be 4 problem sets worth 10% each -- Problem sets will be 3-4 questions long, typically from the Phaneuf and Requate book -- You will have at least 1 week to complete each problem set --- # Final project There is a final project for the course aimed to get you moving toward research -- You can choose one of two options: 1) Literature Review 2) Data dive --- # Final project: lit review Write a literature review on up to 5 papers all in a particular subfield of environmental and resource economics -- - What are the findings? Common threads? Work yet to be done? - You'll need to run the papers by me before committing -- You will present your literature review to the class -- More details later --- # Final project: data dive Find a new data set that we will not use in class but is useful for environmental economics -- - What are the data? How do you get them? How do you use them? What makes them relevant for economics? - You'll need to run it by me -- Do some preliminary analyses on the data -- Present the dataset to the class -- More details later --- # Course schedule: Theory 1. Micro & math recap, theory of externalities 2. Intro to the theory of environmental policy 3. Intro to the theory of environmental policy 4. Imperfect information 5. Competitive output markets 6. Non-competitive output markets 7. Pre-existing distortions 8. Theory of applied welfare economics 9. Theory of applied welfare economics 10. Revealed preference models 11. Hedonics (theory) 12. Extra theory prelim office hours --- # Course schedule: Empirics 13. R and the tidyverse, causal inference 14. R and the tidyverse, causal inference, RCTs 15. Deforestation, remote sensing/simple features, regression discontinuity 16. Hedonics (applied) 17. Climate change science 18. Climate change and the Ricardian Model 19. Climate change and two-way fixed effects 20. Environmental health, difference-in-differences, and event studies 21. Environmental health, difference-in-differences, and event studies 22. Perverse incentives, clean air act, remote sensing 23. Extra empirical prelim office hours --- # Part 1: Math and micro review Before getting into the core material we need to review the mathematical foundations underpinning the economics -- What is central to economic decisionmaking is .hi-blue[constrained optimization] -- - We want to max utility subject to a budget - We want to max profits subject to a constraining regulation - We want to max social welfare subject to an environmental target - We want to minimize costs subject to meeting electricity demand - Etc --- # Unconstrained optimization .hi-blue[Unconstrained optimization] is just Calculus 101 -- Suppose we want to maximize utility from eating fruit: -- $$ \max_{x_1,...,x_N \in \mathbf{A}} U(\mathbf{x}) $$ where `\(U(\mathbf{x}):\mathbb{R}^N \rightarrow\mathbb{R}\)` -- .b[Theorem]: Let `\(U\)` be once continuously-differentiable ( `\(\mathbb{C}^1\)` ) so that first partial derivatives exist and are continuous. If `\(x^*\)` is a local maximum of `\(U\)` on `\(A\)` then -- `$${\partial U(\mathbf{x}^*) \over \partial x_i} = 0 \text{ for } i = 1,...,N$$` --- # Unconstrained optimization What does this theorem tell us? -- That the first-order conditions give us the .hi-blue[necessary conditions] for the utility-maximizing amount of each type of fruit to eat -- These conditions .b[must] be satisfied for any bundle that maximizes utility -- In a logical statement, .ex[if X then Y], Y is the necessary condition: Y .b[must] be true for X to be true X is the .hi-blue[sufficient condition] --- # Unconstrained optimization <style type="text/css"> .panelset { --panel-tab-color: currentColor; --panel-tab-color-active: currentColor; --panel-tab-color-hover: currentColor; --panel-tabs-border-bottom: #ddd; --panel-tab-inactive-opacity: 0.25; --panel-tab-font-family: Roboto; } </style> .pull-left[ `$${\partial U(\mathbf{x}^*) \over \partial x_i} = 0 \text{ for } i = 1,...,N$$` Our necessary conditions tell us that the marginal utility of each fruit equals zero at the optimal choice If `\(x^*\)` is a maximum of `\(U\)` on `\(A\)`, then the tangent line/plane of `\(U\)` at `\((U(x^*), x^*)\)` must be horizontal ] .pull-right[ ![Tangent line at the optimum has 0 slope](1-micro-math_files/figure-html/plot_foc-1.png) ] --- # Unconstrained optimization Do necessary conditions guarantee that we have found the utility-maximizing bundle of fruit? -- .hi-red[NO!] -- They are necessary but not .hi-red[sufficient]: you can come up with counter-examples where a function's derivative equals zero but it is not maximized ( e.g. `\(x^3\)` ) -- We need additional conditions to impose sufficiency --- # Unconstrained optimization These are the second-order sufficient conditions -- .b[Theorem]: Let `\(U\)` be twice continuously differentiable. Suppose that `\(x^*\)` is a critical point of `\(U\)` on `\(A\)` and its Hessian matrix is negative (semi-)definite at `\(x^*\)` ( `\(D^2 U(x^*)\)` is negative (semi-)definite ). Then `\(x^*\)` is a strict (weak) local maximum. -- Negative semi-definite is basically just saying that a multivariate function is weakly concave --- # Unconstrained optimization <style type="text/css"> .panelset { --panel-tab-color: currentColor; --panel-tab-color-active: currentColor; --panel-tab-color-hover: currentColor; --panel-tabs-border-bottom: #ddd; --panel-tab-inactive-opacity: 0.25; --panel-tab-font-family: Roboto; } </style> .panelset[ .panel[.panel-name[Words Details] We need second-order conditions to guarantee we have found a maximum We need marginal utility to be .b[decreasing] (i.e. utility be concave) at `\(x^*\)` This guarantees `\(x^*\)` maximizes `\(U\)` if `\(x^*\)` satisfies the first-order necessary conditions ] .panel[.panel-name[Math Details] Approximate `\(U\)` around `\(x^*\)` with a second-order Taylor expansions: `$$U(x^*+h) = U(x^*) + DU(x^*)h + {1 \over 2} h^TD^2U(x^*)h + O(h^2)$$` `\(DU(x^*) = 0\)` by definition of `\(x^*\)` so that `$$U(x^*+h)-U(x^*) = {1\over2} h^T D^2U(x^*)h$$` `\(U\)` is always decreasing away from `\(x^*\)` if `\({1\over2}h^T D^2U(x^*)h < 0\)` ] ] --- # Constrained optimization Before we were able to eat as much fruit as we wanted -- What if our actions are now constrained? -- $$ \max_{x_1,...,x_N \in \mathbf{A}} U(\mathbf{x}), \,\,\,\,\, A = \\{ \mathbf{x} \in \mathbb{R}^n: h_1(\mathbf{x}) = a_1, \dots, h_m(\mathbf{x}) = a_m \\}$$ where `\(m < n\)` --- # Constrained optimization .pull-left[ A simple and familiar example is utility maximization: $$ \max_{x_1,x_2} U(x_1,x_2) \text{ subject to } h(x_1, x_2) = a $$ We want to be on the .hi-blue[highest indifference curve] subject to our .hi-red[budget constraint] ] .pull-right[ ![Tangent line at the optimum has 0 slope](1-micro-math_files/figure-html/budget_constraint-1.png) ] --- # Constrained optimization Because of our budget constraint, marginal utility may not equal zero at the utility-maximizing bundle! -- No proof, but for some `\(\lambda\)` we can characterize this bundle by -- `$$DU(x^*_1, x^*_2) - \lambda Dh(x_1^*, x_2^*) = (0,0)$$` and -- `$$h(x_1^*,x_2^*) = a$$` -- We now have 3 equations, and 3 unknowns `\((x^*_1,x^*_2,\lambda^*)\)`, we just transformed our constrained problem into an unconstrained problem --- # Constrained optimization How does this magic happen? -- .hi-blue[Intuition:] We can reframe a constrained optimization problem in an alternative fashion where we allow the agent to pick whatever `\((x_1,x_2)\)` they want, .b[but], they must pay a fine `\(\lambda\)` per unit violation of the restriction -- This gives us an alternative, unconstrained problem, known as a *Lagrangian*: `$$\mathcal{L}(x_1,x_2,\lambda) = \max_{x_1,x_2,\lambda} U(x_1,x_2) - \lambda[h(x_1,x_2) - a]$$` -- Maximize utility, but also pay a fine `\(\lambda\)` for each unit difference between `\(h(x_1,x_2)\)` and `\(a\)` --- # Constrained optimization `$$\max_{x_1,x_2,\lambda} U(x_1,x_2) - \lambda[h(x_1,x_2) - a]$$` with first-order conditions: -- $$ {\partial \mathcal{L} \over \partial x_i} = {\partial U \over \partial x_i} - \lambda {\partial h \over \partial x_i} = 0 \text{ for } i = 1,2$$ -- Notice marginal utility is no longer zero at the optimum allocation unless `\(\lambda = 0\)` --- # Constrained optimization We have one remaining issue: some arbitrary `\(\lambda\)` won't guarantee that the solution of our Lagrangian will match the actual constrained problem -- We need to find a way to pick the .hi-blue[correct] `\(\lambda^*\)` that incentivizes the agent to exactly satisfy the constraint `\(h(x_1,x_2) = a\)` -- In other words, we need a third condition to pin down `\(\lambda^*\)`, this is the feasibility condition: `$${\partial \mathcal{L} \over \partial \lambda} = h(x_1,x_2) - a = 0$$` Which is just the constraint! --- # Constrained optimization We can translate a constrained optimization problem into an unconstrained one (the Lagrangian) by: -- 1. Adding a new variable `\(\lambda\)`, which is called the *Lagrange Multiplier* or the *shadow value* of the constraint -- 2. Adding another first-order condition (feasibility condition) and modifying the original first-order conditions to reflect the constraint -- The intuition for `\(\lambda\)` is that it is the marginal value of loosening (or tightening) the constraint


Introduction
Typography (from the Greek words τύπος typos “form” and γράφειν graphein “to write”) is the art and technique of arranging type to make written language readable and beautiful. The arrangement of type involves selecting typefaces, point size, line length, line-spacing (leading), letter-spacing (tracking), and adjusting the space within letters pairs (kerning). Type design is a closely related craft, sometimes considered part of typography; most typographers do not design typefaces, and some type designers do not consider themselves typographers. In modern times, typography has been put in film, television and online broadcasts to add emotion to communication.
Donec scelerisque urna nibh, et interdum ex pellentesque tincidunt. Morbi lorem felis, dapibus ac eleifend id, commodo at diam. Praesent finibus velit est, eget posuere nisi sodales eget. Nunc iaculis euismod malesuada. Aenean vitae sample link mauris eu lacus strong text tempor consequat italic sample nec eu justo. Nullam convallis, lacus pretium blandit facilisis, leo elit aliquet urna, non cursus est odio ut purus. Quisque consequat posuere est id viverra.
Is a closely related craft, sometimes considered part of typography; most typographers do not design typefaces, and some type designers do not consider themselves typographers. In modern times, typography has been put in film, television and online broadcasts to add emotion to communication.
Proin libero justo, sollicitudin dictum sagittis eu, gravida vel erat. Mauris pharetra odio nec nisi ullamcorper bibendum. Aenean pharetra fermentum semper. Etiam maximus, leo ac facilisis egestas, dolor lacus condimentum purus, quis consequat orci justo vitae nunc. Cras tortor mauris, finibus vitae tortor in, porta fermentum orci. Pellentesque bibendum pharetra maximus. Donec vitae porttitor mi. Cras mollis magna eu neque porta, ac mattis sem faucibus.
Is a closely related craft, sometimes considered part of typography; most typographers do not design typefaces, and some type designers do not consider themselves typographers. In modern times, typography has been put in film, television and online broadcasts to add emotion to communication.
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- In posuere risus eget velit finibus luctus.
- Praesent lacinia nunc et fringilla condimentum.
- Vivamus sed ipsum facilisis, maximus magna eu, consequat odio.
- Etiam auctor ipsum nec consectetur venenatis.
- Praesent lacinia nunc et fringilla condimentum
Unordered List:
- Phasellus posuere libero non velit sodales, sed efficitur nisi iaculis.
- Donec ut est eget ex vehicula egestas a eget urna.
- Vestibulum vulputate purus in posuere imperdiet.
- Mauris varius erat sed sagittis placerat.
- Cras bibendum libero sagittis suscipit imperdiet.
Blockquote
Computer technology revolutionized typography in the 20th century. Personal computers in the 1980s like the Macintosh allowed type designers to create types digitally using commercial graphic design software. Digital technology also enabled designers to create more experimental typefaces, alongside the practical fonts of traditional typography. Designs for typefaces could be created faster with the new technology, and for more specific functions. The cost for developing typefaces was drastically lowered, becoming widely available to the masses. The change has been called the “democratization of type” and has given new designers more opportunities to enter the field.
Painting is concerned with all the 10 attributes of sight; which are: Darkness, Light, Solidity and Colour, Form and Position, Distance and Propinquity, Motion and Rest.
Typography is performed by typesetters, compositors, typographers, graphic designers, art directors, manga artists, comic book artists, graffiti artists, clerical workers, and everyone else who arranges type for a product. Until the Digital Age, typography was a specialized occupation. Digitization opened up typography to new generations of visual designers and lay users, and David Jury, Head of Graphic Design at Colchester Institute in England, states that “typography is now something everybody does.”


A simple Asteroids game using Ash Framework, HTML5 Canvas, CreateJS, and three.js
Ash Framework, originally written for ActionScript 3, is an entity-component system for game development.
It's a way to organise and manage your game code without sacrificing the game performance.
For more information about Ash Framework, including introductory articles, checkout its official page at http://www.ashframework.org/.
Ashteroids source code is available at GitHub


Honor V30 live photos reveal the smartphone in all its glory - Gizchina.com
by Marco LancasterHonor V30 live photos reveal the smartphone in all its glory
3.8 (76.67%) 6 votes
Honor is gearing up to reveal the Honor V30 and V30 tomorrow in China. During the last few days, we have been machine-gunned with several leaks of the Honor V30 revealing its design and some of the specifications. We’re just one day from the actual release, but things can’t be different even in the last hours. The Honor V30 has bee spotted in a couple of leaked shots that reveal the handset in all its glory.
The images appeared on Weibo, and since November 25 date appears in the V30 visor we can say that they are really fresh. The picture confirms the pill-shaped punch-hole enabled the display that will serve as a house for the dual-selfie snappers. The bezels are really slim, so the rumored 91.46% screen-to-body ratio seems accurate here. Moving around to the back we can see the triple-camera setup that is fitted in a vertical alignment. The volume rocker can be seen on the right edge of the device. In addition, we can see the side-mounted fingerprint scanner which is just below the volume buttons. The second shot reveals the retail package which boasts the “Vera” name.
Honor V30 5G specifications:
According to the recent leaks and rumors, the V30 5G will ship with a Kirin 990 5G SoC underneath a FullHD+ IPS LCD display of 6.57-inch. Furthermore, the handset will come in 6GB/8GB of RAM and up to 128GB of Internal Storage. Apparently it draws power from a 4,200mAh battery with 40W fast charging support. There is Android 10-based with Honor’s MagicUI running atop.
The details about the V30 front-facing cameras remain a mystery. When it comes to the rear setup it may come with a 40MP Sony IMX686 + 8MP telephoto + OIS 8MP wide-angle modules. Last but not least, the handset should come in Icelandic Fantasy, Magic Night Star River, Charm Star Blue and Twilight Orange colors.
We’ll know everything about the Honor V30 5G and V30 Pro 5G tomorrow. But keep an eye in the headlines to see if new leaks will pop-out in the coming days.


Reports meta annotations which are used via reflection by frameworks, but their retention policy is not RUNTIME.
If a retention policy is not specified, then the default retention policy 'CLASS' will be used.
Such annotations will not be visible at runtime.
New in 2017.2


Objective and Description
Objective: We will review adding and subtracting fractions with unlike denominators.
Description: This learning module will help you add and subtract fractions with fun videos
and practice activities.
Objective: We will review adding and subtracting fractions with unlike denominators.
Description: This learning module will help you add and subtract fractions with fun videos
and practice activities.


Test images are available for most formats supported by the library. Most of the images included in the test kit are also part of this documentation (albeit in TIFF rather than GIF or JFIF). The images are kept in a separate archive that should be located in the same directory as this software. The latest archive of test images is located at ftp://ftp.sgi.com/graphics/tiff/v3.0pics.tar.Z.
There are two other good sources for TIFF test images: the contributed software contrib/dbs includes several programs that generate test images suitable for debugging, and the tiffcp program can be used to generate a variety of images with different storage characteristics.


New Image Youth Center
New Image Youth Center (NIYC) is a non-profit organization established in 2004 in Parramore community, Orlando. Its mission is to change the path of at-risk youth through education and example.
I was volunteering with Ad2Orlando public service team consisting of six members. My role was to design and develop the website alongside one other member.
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NIYC wants a redesign of their website to attract donations. They also want their website to reflect their story and the work they do.
NIYC wants to target donors in the community with a special focus on corporate donors.
As a team, we first evaluated their existing website to determine the problems. Then we came up with the following list
In addition, we planned on fixing the problems we found during usability evaluation.
We wanted to give the website a modern look. So, we chose two san-serif fonts that paired well together. Montserrat was chosen for the geometric simplicity of its letters, especially the capitals. We chose Open Sans for body copy as it has excellent legibility characteristics in its letter forms. For the storybook, we used Permanent marker as display text to give it a handwritten look.
As a team, we had to come up with the content for the storybook. So, we decided to come up with surveys for each age group at NIYC. We wanted to capture the personality and interests of the kids there. We also wanted to know their view on NIYC and how it helps them everyday. After some brainstorming, we came up with a set of questions like
Since it was tough to get hold of all the kids at the same time to handout surveys, we decided to add the survey pages online. Also, we setup a mail chimp campaign and captured their email addresses for future correspondence.
After a week, we had 82 surveys filled. We then organized photo sessions at NIYC. We had a candid photo session and were able to capture high quality pictures of the kids that we could use on the website. We then put up the storybook page with pictures of the kids along with a summary of their responses.
The client was very happy with the outcome of the website. We delivered it on time. Since this was part of the Ad2 Orlando public service campaign, we presented this campaign in the Ad2 public service advertising competition. We secured 3rd place for this project nationally.
The idea of the story book impressed everyone. So, We are planning to generate pages, for students, in the storybook based on the information we have gathered.


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What can I help you with?
I am currently open to work on small to medium sized projects.
Examples of things I've done in the past include:
- mobile-ready webites for restaurants and small businesses
- personal portfolio websites
- web application MVPs
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Whatever your project, you can schedule a free 15 minute consultation with me to chat about how I can be of service. I may even be able to direct you to another service that can better meet your needs.


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Go ahead, make it a “round” trip! This new duffel offers a unique round shape that makes it so easy to pack. Three multifunction interior pockets keep smaller items organized, while a front and side slip pocket keeps essentials always conveniently within reach.
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| Weight: | 0.3 kg |
| Dimensions: | 20 ½" W x 12" H x 10 ¾" D with 9" strap drop and 52" removable, adjustable strap |
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| Care Tips: | Machine wash cold, gentle cycle, only non-chlorine bleach when needed; line dry |
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js-ipfs-http-client
name.publish()
and
name.resolve()
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Enter the multiaddr of a IPFS HTTP API.
Connect
Add a new file to IPFS and publish it.
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Publish an existing file or directory from IPFS.
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