diff --git a/_thesis/4-8-acknowledgements-2.html b/_thesis/4-8-acknowledgements-2.html
deleted file mode 100644
index 9c2a677..0000000
--- a/_thesis/4-8-acknowledgements-2.html
+++ /dev/null
@@ -1,259 +0,0 @@
-<!DOCTYPE html>
-<html xmlns="http://www.w3.org/1999/xhtml" lang="" xml:lang="">
-<head>
-
-  <meta charset="utf-8" />
-  <meta http-equiv="X-UA-Compatible" content="IE=edge" />
-  <title>4.8 Acknowledgements | Tidy tools for supporting fluent workflow in temporal data analysis</title>
-  <meta name="description" content="4.8 Acknowledgements | Tidy tools for supporting fluent workflow in temporal data analysis" />
-  <meta name="generator" content="bookdown 0.13 and GitBook 2.6.7" />
-
-  <meta property="og:title" content="4.8 Acknowledgements | Tidy tools for supporting fluent workflow in temporal data analysis" />
-  <meta property="og:type" content="book" />
-  
-  
-  
-  
-
-  <meta name="twitter:card" content="summary" />
-  <meta name="twitter:title" content="4.8 Acknowledgements | Tidy tools for supporting fluent workflow in temporal data analysis" />
-  
-  
-  
-
-<meta name="author" content="Earo Wang" />
-
-
-
-  <meta name="viewport" content="width=device-width, initial-scale=1" />
-  <meta name="apple-mobile-web-app-capable" content="yes" />
-  <meta name="apple-mobile-web-app-status-bar-style" content="black" />
-  
-  
-<link rel="prev" href="4-7-sec-mists-conclusion.html"/>
-<link rel="next" href="5-ch-conclusion.html"/>
-<script src="libs/jquery-2.2.3/jquery.min.js"></script>
-<link href="libs/gitbook-2.6.7/css/style.css" rel="stylesheet" />
-<link href="libs/gitbook-2.6.7/css/plugin-table.css" rel="stylesheet" />
-<link href="libs/gitbook-2.6.7/css/plugin-bookdown.css" rel="stylesheet" />
-<link href="libs/gitbook-2.6.7/css/plugin-highlight.css" rel="stylesheet" />
-<link href="libs/gitbook-2.6.7/css/plugin-search.css" rel="stylesheet" />
-<link href="libs/gitbook-2.6.7/css/plugin-fontsettings.css" rel="stylesheet" />
-
-
-
-
-
-
-
-<script src="libs/kePrint-0.0.1/kePrint.js"></script>
-
-
-<style type="text/css">
-a.sourceLine { display: inline-block; line-height: 1.25; }
-a.sourceLine { pointer-events: none; color: inherit; text-decoration: inherit; }
-a.sourceLine:empty { height: 1.2em; }
-.sourceCode { overflow: visible; }
-code.sourceCode { white-space: pre; position: relative; }
-pre.sourceCode { margin: 0; }
-@media screen {
-div.sourceCode { overflow: auto; }
-}
-@media print {
-code.sourceCode { white-space: pre-wrap; }
-a.sourceLine { text-indent: -1em; padding-left: 1em; }
-}
-pre.numberSource a.sourceLine
-  { position: relative; left: -4em; }
-pre.numberSource a.sourceLine::before
-  { content: attr(data-line-number);
-    position: relative; left: -1em; text-align: right; vertical-align: baseline;
-    border: none; pointer-events: all; display: inline-block;
-    -webkit-touch-callout: none; -webkit-user-select: none;
-    -khtml-user-select: none; -moz-user-select: none;
-    -ms-user-select: none; user-select: none;
-    padding: 0 4px; width: 4em;
-    color: #aaaaaa;
-  }
-pre.numberSource { margin-left: 3em; border-left: 1px solid #aaaaaa;  padding-left: 4px; }
-div.sourceCode
-  {  }
-@media screen {
-a.sourceLine::before { text-decoration: underline; }
-}
-code span.al { color: #ff0000; font-weight: bold; } /* Alert */
-code span.an { color: #60a0b0; font-weight: bold; font-style: italic; } /* Annotation */
-code span.at { color: #7d9029; } /* Attribute */
-code span.bn { color: #40a070; } /* BaseN */
-code span.bu { } /* BuiltIn */
-code span.cf { color: #007020; font-weight: bold; } /* ControlFlow */
-code span.ch { color: #4070a0; } /* Char */
-code span.cn { color: #880000; } /* Constant */
-code span.co { color: #60a0b0; font-style: italic; } /* Comment */
-code span.cv { color: #60a0b0; font-weight: bold; font-style: italic; } /* CommentVar */
-code span.do { color: #ba2121; font-style: italic; } /* Documentation */
-code span.dt { color: #902000; } /* DataType */
-code span.dv { color: #40a070; } /* DecVal */
-code span.er { color: #ff0000; font-weight: bold; } /* Error */
-code span.ex { } /* Extension */
-code span.fl { color: #40a070; } /* Float */
-code span.fu { color: #06287e; } /* Function */
-code span.im { } /* Import */
-code span.in { color: #60a0b0; font-weight: bold; font-style: italic; } /* Information */
-code span.kw { color: #007020; font-weight: bold; } /* Keyword */
-code span.op { color: #666666; } /* Operator */
-code span.ot { color: #007020; } /* Other */
-code span.pp { color: #bc7a00; } /* Preprocessor */
-code span.sc { color: #4070a0; } /* SpecialChar */
-code span.ss { color: #bb6688; } /* SpecialString */
-code span.st { color: #4070a0; } /* String */
-code span.va { color: #19177c; } /* Variable */
-code span.vs { color: #4070a0; } /* VerbatimString */
-code span.wa { color: #60a0b0; font-weight: bold; font-style: italic; } /* Warning */
-</style>
-
-<link rel="stylesheet" href="template/style.css" type="text/css" />
-</head>
-
-<body>
-
-
-
-  <div class="book without-animation with-summary font-size-2 font-family-1" data-basepath=".">
-
-    <div class="book-summary">
-      <nav role="navigation">
-
-<ul class="summary">
-<li><strong><a href="./">Temporal tidy tools</a></strong></li>
-
-<li class="divider"></li>
-<li class="chapter" data-level="" data-path="index.html"><a href="index.html"><i class="fa fa-check"></i>Welcome</a></li>
-<li class="chapter" data-level="" data-path="abstract.html"><a href="abstract.html"><i class="fa fa-check"></i>Abstract</a></li>
-<li class="chapter" data-level="" data-path="acknowledgements.html"><a href="acknowledgements.html"><i class="fa fa-check"></i>Acknowledgements</a></li>
-<li class="chapter" data-level="" data-path="preface.html"><a href="preface.html"><i class="fa fa-check"></i>Preface</a></li>
-<li class="chapter" data-level="1" data-path="1-ch-intro.html"><a href="1-ch-intro.html"><i class="fa fa-check"></i><b>1</b> Introduction</a><ul>
-<li class="chapter" data-level="1.1" data-path="1-1-sec-calendar-vis.html"><a href="1-1-sec-calendar-vis.html"><i class="fa fa-check"></i><b>1.1</b> Calendar-based graphics</a></li>
-<li class="chapter" data-level="1.2" data-path="1-2-sec-tsibble.html"><a href="1-2-sec-tsibble.html"><i class="fa fa-check"></i><b>1.2</b> Tidy temporal data structure</a></li>
-<li class="chapter" data-level="1.3" data-path="1-3-sec-mists.html"><a href="1-3-sec-mists.html"><i class="fa fa-check"></i><b>1.3</b> Missingness in time</a></li>
-<li class="chapter" data-level="1.4" data-path="1-4-summary.html"><a href="1-4-summary.html"><i class="fa fa-check"></i><b>1.4</b> Summary</a></li>
-</ul></li>
-<li class="chapter" data-level="2" data-path="2-ch-calendar-vis.html"><a href="2-ch-calendar-vis.html"><i class="fa fa-check"></i><b>2</b> Calendar-based graphics for visualizing people’s daily schedules</a><ul>
-<li class="chapter" data-level="2.1" data-path="2-1-introduction.html"><a href="2-1-introduction.html"><i class="fa fa-check"></i><b>2.1</b> Introduction</a></li>
-<li class="chapter" data-level="2.2" data-path="2-2-sec-algorithm.html"><a href="2-2-sec-algorithm.html"><i class="fa fa-check"></i><b>2.2</b> Creating a calendar display</a></li>
-<li class="chapter" data-level="2.3" data-path="2-3-sec-case.html"><a href="2-3-sec-case.html"><i class="fa fa-check"></i><b>2.3</b> Case study</a></li>
-<li class="chapter" data-level="2.4" data-path="2-4-sec-discussion.html"><a href="2-4-sec-discussion.html"><i class="fa fa-check"></i><b>2.4</b> Discussion</a></li>
-<li class="chapter" data-level="" data-path="acknowledgements-1.html"><a href="acknowledgements-1.html"><i class="fa fa-check"></i>Acknowledgements</a></li>
-</ul></li>
-<li class="chapter" data-level="3" data-path="3-ch-tsibble.html"><a href="3-ch-tsibble.html"><i class="fa fa-check"></i><b>3</b> A new tidy data structure to support exploration and modeling of temporal data</a><ul>
-<li class="chapter" data-level="3.1" data-path="3-1-sec-intro.html"><a href="3-1-sec-intro.html"><i class="fa fa-check"></i><b>3.1</b> Introduction</a></li>
-<li class="chapter" data-level="3.2" data-path="3-2-sec-str.html"><a href="3-2-sec-str.html"><i class="fa fa-check"></i><b>3.2</b> Data structures</a></li>
-<li class="chapter" data-level="3.3" data-path="3-3-sec-semantics.html"><a href="3-3-sec-semantics.html"><i class="fa fa-check"></i><b>3.3</b> Contextual semantics</a></li>
-<li class="chapter" data-level="3.4" data-path="3-4-sec-pipeline.html"><a href="3-4-sec-pipeline.html"><i class="fa fa-check"></i><b>3.4</b> Temporal data pipelines</a></li>
-<li class="chapter" data-level="3.5" data-path="3-5-sec-software.html"><a href="3-5-sec-software.html"><i class="fa fa-check"></i><b>3.5</b> Software structure and design decisions</a></li>
-<li class="chapter" data-level="3.6" data-path="3-6-sec-cases.html"><a href="3-6-sec-cases.html"><i class="fa fa-check"></i><b>3.6</b> Case studies</a></li>
-<li class="chapter" data-level="3.7" data-path="3-7-sec-conclusion.html"><a href="3-7-sec-conclusion.html"><i class="fa fa-check"></i><b>3.7</b> Conclusion and future work</a></li>
-<li class="chapter" data-level="" data-path="acknowledgments.html"><a href="acknowledgments.html"><i class="fa fa-check"></i>Acknowledgments</a></li>
-</ul></li>
-<li class="chapter" data-level="4" data-path="4-ch-mists.html"><a href="4-ch-mists.html"><i class="fa fa-check"></i><b>4</b> Data representation, visual and analytical techniques for demystifying temporal missing data</a><ul>
-<li class="chapter" data-level="4.1" data-path="4-1-sec-mists-intro.html"><a href="4-1-sec-mists-intro.html"><i class="fa fa-check"></i><b>4.1</b> Introduction</a></li>
-<li class="chapter" data-level="4.2" data-path="4-2-sec-mists-categories.html"><a href="4-2-sec-mists-categories.html"><i class="fa fa-check"></i><b>4.2</b> Categories of temporal missing data</a></li>
-<li class="chapter" data-level="4.3" data-path="4-3-sec-mists-na-rle.html"><a href="4-3-sec-mists-na-rle.html"><i class="fa fa-check"></i><b>4.3</b> New data abstraction and operations for missing data in time</a></li>
-<li class="chapter" data-level="4.4" data-path="4-4-sec-mists-vis.html"><a href="4-4-sec-mists-vis.html"><i class="fa fa-check"></i><b>4.4</b> Visual methods for exploring temporal missingness</a></li>
-<li class="chapter" data-level="4.5" data-path="4-5-sec-mists-polish.html"><a href="4-5-sec-mists-polish.html"><i class="fa fa-check"></i><b>4.5</b> Scaling up to large collections of temporal data</a></li>
-<li class="chapter" data-level="4.6" data-path="4-6-sec-mists-data.html"><a href="4-6-sec-mists-data.html"><i class="fa fa-check"></i><b>4.6</b> Applications</a></li>
-<li class="chapter" data-level="4.7" data-path="4-7-sec-mists-conclusion.html"><a href="4-7-sec-mists-conclusion.html"><i class="fa fa-check"></i><b>4.7</b> Conclusion</a></li>
-<li class="chapter" data-level="4.8" data-path="4-8-acknowledgements-2.html"><a href="4-8-acknowledgements-2.html"><i class="fa fa-check"></i><b>4.8</b> Acknowledgements</a></li>
-</ul></li>
-<li class="chapter" data-level="5" data-path="5-ch-conclusion.html"><a href="5-ch-conclusion.html"><i class="fa fa-check"></i><b>5</b> Conclusion and future plans</a><ul>
-<li class="chapter" data-level="5.1" data-path="5-1-software-development.html"><a href="5-1-software-development.html"><i class="fa fa-check"></i><b>5.1</b> Software development</a></li>
-<li class="chapter" data-level="5.2" data-path="5-2-future-work.html"><a href="5-2-future-work.html"><i class="fa fa-check"></i><b>5.2</b> Future work</a></li>
-<li class="chapter" data-level="5.3" data-path="5-3-final-words.html"><a href="5-3-final-words.html"><i class="fa fa-check"></i><b>5.3</b> Final words</a></li>
-</ul></li>
-<li class="appendix"><span><b>Appendix</b></span></li>
-<li class="chapter" data-level="A" data-path="A-data-dictionary.html"><a href="A-data-dictionary.html"><i class="fa fa-check"></i><b>A</b> Data dictionary</a></li>
-<li class="chapter" data-level="" data-path="bibliography.html"><a href="bibliography.html"><i class="fa fa-check"></i>Bibliography</a></li>
-<li class="divider"></li>
-<li><strong><a href="https://github.com/rstudio/bookdown" target="blank">Proudly published with bookdown</a></strong></li>
-
-</ul>
-
-      </nav>
-    </div>
-
-    <div class="book-body">
-      <div class="body-inner">
-        <div class="book-header" role="navigation">
-          <h1>
-            <i class="fa fa-circle-o-notch fa-spin"></i><a href="./">Tidy tools for supporting fluent workflow in temporal data analysis</a>
-          </h1>
-        </div>
-
-        <div class="page-wrapper" tabindex="-1" role="main">
-          <div class="page-inner">
-
-            <section class="normal" id="section-">
-<div id="acknowledgements-2" class="section level2">
-<h2><span class="header-section-number">4.8</span> Acknowledgements</h2>
-<p>This article was created with knitr <span class="citation">(Xie <a href="bibliography.html#ref-knitr">2015</a>)</span> and R Markdown <span class="citation">(Xie, Allaire, and Grolemund <a href="bibliography.html#ref-rmarkdown">2018</a>)</span>. The <strong>mists</strong> R package is available on Github <a href="https://github.com/earowang/mists" class="uri">https://github.com/earowang/mists</a>.</p>
-
-</div>
-<!-- </div> -->
-            </section>
-
-          </div>
-        </div>
-      </div>
-<a href="4-7-sec-mists-conclusion.html" class="navigation navigation-prev " aria-label="Previous page"><i class="fa fa-angle-left"></i></a>
-<a href="5-ch-conclusion.html" class="navigation navigation-next " aria-label="Next page"><i class="fa fa-angle-right"></i></a>
-    </div>
-  </div>
-<script src="libs/gitbook-2.6.7/js/app.min.js"></script>
-<script src="libs/gitbook-2.6.7/js/lunr.js"></script>
-<script src="libs/gitbook-2.6.7/js/plugin-search.js"></script>
-<script src="libs/gitbook-2.6.7/js/plugin-sharing.js"></script>
-<script src="libs/gitbook-2.6.7/js/plugin-fontsettings.js"></script>
-<script src="libs/gitbook-2.6.7/js/plugin-bookdown.js"></script>
-<script src="libs/gitbook-2.6.7/js/jquery.highlight.js"></script>
-<script>
-gitbook.require(["gitbook"], function(gitbook) {
-gitbook.start({
-"sharing": false,
-"fontsettings": {
-"theme": "white",
-"family": "sans",
-"size": 2
-},
-"edit": {
-"link": "https://github.com/earowang/thesis/edit/master/Rmd//04-mists.Rmd",
-"text": "Edit"
-},
-"history": {
-"link": null,
-"text": null
-},
-"download": null,
-"toc": {
-"collapse": "none"
-}
-});
-});
-</script>
-
-<!-- dynamically load mathjax for compatibility with self-contained -->
-<script>
-  (function () {
-    var script = document.createElement("script");
-    script.type = "text/javascript";
-    var src = "true";
-    if (src === "" || src === "true") src = "https://mathjax.rstudio.com/latest/MathJax.js?config=TeX-MML-AM_CHTML";
-    if (location.protocol !== "file:")
-      if (/^https?:/.test(src))
-        src = src.replace(/^https?:/, '');
-    script.src = src;
-    document.getElementsByTagName("head")[0].appendChild(script);
-  })();
-</script>
-</body>
-
-</html>
