Category Archives: Main Blog

Summer intern dives deep into someone else’s code

In his spare time, Saul Amster likes to program. He’s currently working on a project to turn a tablet into a magic mirror. Yes, like Snow White’s evil stepmother (“Mirror, mirror on the wall…”), except imagine asking the mirror for the day’s forecast or the score of last night’s game. “Programming is an interesting hobby,” he says. “It’s basically free. All you need is a computer. Other hobbies require you to keep sinking money into them.”

This summer, Saul turned his programming hobby into an internship at the Concord Consortium. But while he’s used other external software libraries before, he had to teach himself to work with other people’s preexisting code, plus learn the push and pull requests of contributing code on GitHub. And although he was new to the code base underlying the Seismic Explorer software, which displays earthquakes and volcanoes worldwide using real-time data from the USGS, he didn’t let that stop him from jumping in. In fact, he’s enhanced an existing feature by redrawing the plate boundaries to make them more noticeable and added a new feature that shows arrows to display the movement of the tectonic plates. He’s now reworking how the animation is done in the model.

“I have been really impressed with Saul,” says Amy Pallant, Principal Investigator of the Geological Models for Explorations of Dynamic Earth (GEODE) project, which developed Seismic Explorer. “He has been able to add new data into the model, think about the user experience, and help me make decisions about layout, design, and data representation. His vast experience with programming, computer games and educational environments meant that I could learn from him, too.”

Saul is sure this first experience working with someone else’s code will serve him well when he heads off to Ithaca College as a freshman computer science major. “This has been super helpful for classes and for future jobs,” he says. He’s not at all worried about his freshman Java course, since he has already learned the language. It’s one of his favorites, along with C#, which he uses in his videogame programming.

Saul is excited about some high-end virtual reality gear he spotted in the computer department at Ithaca. He’s already made some small VR apps for the Google cardboard, and he’s looking forward to research opportunities. So along with clothes and toothpaste, he’s packing his laptop and external graphics box—with better cooling and more power, it’s perfect for developing (and playing) games, and getting his homework done, of course.

 

Mechanical design and paper crafting combine in Paper Mechatronics

How can you make a cardboard owl that flaps its wings? Or a paper flower that blooms? With funding from the National Science Foundation, we are working with the University of Colorado’s Craft Technology Lab and the Children’s Creativity Museum in San Francisco to study and enhance the engineering education potential of Paper Mechatronics, an innovative educational technology genre that mixes creative papercrafts, mechanical design, and computational thinking. Soon, young learners will be designing real and fantastical paper inventions of their own imagination and animate them with mechanical motions.

The new two-year project builds off an earlier project by Principal Investigators Sherry Hsi and Michael Eisenberg, which prototyped several Paper Mechatronics design projects, organized activity formats, and piloted the various design elements with children and adults to determine which worked best to inspire learning and teach design. These included a custom software design tool, simple hardware modules, cardboard electronics, sample workshop formats, and project ideas. Early Paper Mechatronics activities—from a percussion workshop to a cereal hackathon and a Robot Petting Zoo—showed encouraging results with after school youth (ages 12-18) and museum visitors.

Mechanical duck designed with Paper Mechatronics.

Robot Petting Zoo.

Paper Mechatronics engaged participants in key engineering design practices (design, build, test), though learners were challenged by translating their visions into mechanical actions. So, to support designers who had no electronics or computer-aided design background and limited computer programming experience, Ph.D. student HyunJoo Oh designed FoldMecha, which generates paper-based templates for a number of design parameters such as shape, size, and type of motor movements that can be cut out with a paper or laser cutter.

 The new project will expand and improve this early Paper Mechatronics design software for modeling mechanical components and movements and create a new Paper Mechatronics kit with instructional resources, electronically enhanced crafting materials, low-cost microcontrollers and accessories, and custom design software.

Our research goal is to explore how to support novice designers in learning from the Paper Mechatronics kit and study how youth develop adaptive expertise, including knowledge-seeking, resourcefulness, confidence, and persistence. We’ll research how on-ramps to engineering design activities like engaging in paper mechatronic design activities help youth develop adaptive expertise and what types of instructional resources and scaffolding are most useful in supporting learners to be creative in engineering design.

Introducing summer intern, data science major Maya Haigis

Before interning with senior scientist Charles Xie this summer, Maya Haigis had no idea how many solar panel manufacturers there are—“There’s a ton!”

A data science major at the University of Rochester, Maya put her analytic skills to work at the Concord Consortium collecting data on solar panels (dimensions, weight, maximum wattage, etc.) and designed a panda solar power plant with Energy3D, an engineering design and simulation tool for renewable energy and energy efficiency. She used Energy3D to create a power plant in the shape of a bald eagle, too.

“Charles heard about the giant panda power plant in Datong, China, in the news, and asked me to replicate it in Energy3D.” Maya says, “It was a good introduction to the features of Energy3D. Charles suggested I do something relevant to the U.S.—like our own national symbol! It was fun imagining flying across the country and seeing a giant bald eagle out of the window instead of the generic rectangles or circles of traditional solar farms.”

She also worked with the Energy3D team modeling local schools and other community buildings for the Solarize Your World curriculum they are designing.

“Maya is a real genius in 3D modeling,” said Charles. “I didn’t expect her to come up with sophisticated 3D structures within a couple of hours with a piece of software that she had never used before. But she did it elegantly. It is remarkable that she has created scores of highly accurate 3D models for school buildings with incredible details.”

Bald eagle solar power in Energy3D (left) and close-up of bald eagle (right).

As a sophomore, Maya is currently on the same path as computer science students, but her curriculum path will soon diverge with a focus on data mining and database systems plus more statistics. She’s always been “a math person,“ she says, but credits her high school AP statistics teacher’s enthusiasm for data and statistics for consolidating her interest.

At the University of Rochester she’s already taken courses in Java, data structures and algorithms, discrete math, calculus, and linear algebra with differential equations. “All data is interesting,” she says, but notes sports stats are particularly fascinating. No surprise, since Maya is a student athlete who plays field hockey at the Division III school where her schedule includes practice six days a week.

She notes, “My brother and I used to have a collection of baseball cards and I would try to memorize the stats of my favorite players. It’s a bit ironic because before games, coaches always say that once you step onto the field, the statistics don’t mean anything and what matters is which team plays the hardest, but I still look through other team stats.”

Recently, Maya had a pivotal experience. She spent half a day at Pfizer working with a business analyst, who serves as a connection between scientists and programmers. “The business analyst would explain to the scientists what the data meant,” she explains. “And if the scientists wanted their data displayed in a certain way, she would talk to the programmers.” Maya can imagine filling a similar liaison role working as data scientist, though she also admits, “I’m not exactly sure what I want to do after college, but I’m looking forward to the data science courses at Rochester, and I’m excited to see what opportunities will arise with big data!”

My Daughter Heard About an Earthquake. How Do I Explain It?

Earthquakes occur worldwide daily, and their aftereffects vary widely, from minimal to devastating. From California to the Mediterranean, some communities live with the threat and consequences of earthquakes and their aftershocks on a regular basis. Understanding what causes an earthquake is not easy. How is it possible to visualize monumental slabs of Earth moving? And why do we need to?

On June 12, 2017, newspapers worldwide reported on a 6.3 magnitude earthquake south of the island of Lesbos, Greece (off the western coast of Turkey). The quake caused widespread structural damage as well as loss of life, and it drew considerable attention, in part, because of the large number of migrants on Lesbos. How to house and care for the affected migrants and residents became a major international challenge.

But according to the USGS, the earthquake was “the result of normal faulting in the shallow crust.” The Lesbos quake was traumatic, but not unexpected. Greece and Turkey are particularly earthquake prone because they are on active fault lines. The Mediterranean region is seismically active due to the convergence of the African plate to the south with the Eurasian plate to the north. The African plate is subducting beneath the Eurasian plate at a place called the Hellenic Trench.

That’s a lot to understand, let alone visualize. When a seismic event occurs, how can a teacher explain such monumental movements of the Earth to middle school students? Typically, it’s been done with drawings and detailed descriptions, such as the excellent resources available from the USGS. But earthquakes and other geologic events are about movement, happening far out of sight. The Concord Consortium’s GEODE project is creating a way to visualize the Earth’s movements using an interactive, dynamic computer model of tectonic plates.

Another GEODE model — the Seismic Explorer — allows users to see the pattern of earthquakes worldwide, including their magnitude and depth. The Lesbos quake and many others, as well as towns and cities, are visible.

The GEODE project is still researching and developing the best ways for kids to learn about Earth’s big movements. But why is it important? Because the consequences of these movements can crumble buildings and cause loss of life. Understanding patterns of Earth’s movement may help lead to better forecasting, preparedness, and response.

Thermal imaging as a universal indicator of chemical reactions: An example of acid-base titration

Fig. 1: NaOH-HCl titration
Funded by the National Science Foundation and in collaboration with Prof. Dunwei Wang's lab at the Department of Chemistry, Boston College, we are exploring the feasibility of using thermal imaging as a universal indicator of chemical reactions. The central tenet is that, as all chemical reactions absorb or release thermal energy (endothermic or exothermic), we can infer certain information from the time evolution and spatial distribution of the temperature field.

To prove the concept, we first chose titration, a common laboratory method of quantitative chemical analysis that is used to determine the unknown concentration of an identified analyte, as a beginning example. A reagent, called the titrant, is prepared as a standard solution. A known concentration and volume of titrant reacts with a solution of analyte to determine its concentration.

The experiment we did today was an acid-base titration. An acid–base titration is the determination of the concentration of an acid or base by exactly neutralizing the acid or base with a base or acid of known concentration. Such a titration is typically done with a burette that drops titrant into an Erlenmeyer flask containing the analyte. A pH indicator is used to determine whether the equivalence point has been reached. The pH indicator usually depends on the analyte and the titrant. But a differential thermal analysis based on infrared imaging may provide a universal indicator as the technique depends only on the heat of reaction and thermal energy is universal.

Fig. 2: The dish-array titration revealed by FLIR ONE
Figures 1 and 2 in this article show the results of the NaOH+HCl titration, taken using a FLIR ONE thermal camera attached to my iPhone 6. A solution of 10% NaOH was prepared as the analyte of "unknown" concentration and 1%, 3%, 5%, 7%, 10%, 12%, 15%, 18%, and 20% HCl were used as the titrant. The experiment was conducted with a 3×3 array of Petri dishes. Hence, we call this setup as dish-array titration. Preliminary results of this first experiment appeared to be encouraging, but we have to be cautious as the dissolving of HCl after the acid-base neutralization completes can also release a significant amount of heat. How to separate the thermal signatures of reaction and dissolving requires some further thinking.

Chinese translation of SageModeler systems dynamics modeling tool

In June, Professor Silvia Wen-Yu Lee and her team at the National Changhua University of Education in Central Taiwan offered a 10-hour modeling curriculum to approximately 100 seventh grade students. Students used a new Chinese language version of SageModeler to model the relationship between marine biology and human activity in a unit about environmental conservation.

SageModeler is a free, web-based systems dynamics modeling tool for middle and high school students to construct dynamic models. SageModeler is being developed by the Building Models project, a collaboration between the Concord Consortium and the CREATE for STEM Institute at Michigan State University (MSU).

Professor Lee met Joe Krajcik, one of the lead writers of the Next Generation Science Standards and Principal Investigator (PI) of the Building Models project at MSU, where she had served as a visiting professor in 2014. Dan Damelin is the project’s PI at the Concord Consortium. Thanks to this fortuitous collaboration, Lee and her team translated SageModeler into Chinese, and her students are now taking advantage of this easy-to-use tool to create dynamic systems models.

Students building models with SageModeler. 

“The students learned how to draw models instantly after a brief demonstration,” Lee noted. “Our teachers were amazed by the students’ level of engagement and by the students’ attention to the relationships when they are working together on the SageModeler. ” Professor Lee and her colleagues at the National Changhua University of Education hope to understand how the students develop competencies in model building and whether they develop clear understandings of the causal and dynamic relationships in marine biology and human activity (fishing) through modeling.

Sample student model from a seventh grade Taiwanese student.

You can build your own model in five easy steps.

  1. Open SageModeler (in English or Chinese)

  2. Add variables to the canvas First, brainstorm factors that affect marine biology. What contributes to it and what is affected by it? Now, add images for each variable to the canvas.

  3. Link variables and set relationships Draw links from one variable to another and select from a menu to set the relationships between those variables. By using words and pictures of graphs, students can define the underlying equations that will be used to run the model.

  4. Run the model Open the simulation controls and run the model to collect data. Adjust the model settings to see how changing the variables affects the outcome. Does the model output data make sense? Does it match real-world data? Are the relationships between variables set up appropriately?

  5. Revise and expand your model Revise your model to better match the phenomenon you are modeling. For example, you may want to add more variables. As you continue to ask new questions, you can revise your model and deepen your understanding of the system.

We are currently working on additional internationalization efforts, including Turkish and Spanish translations. Interested in learning more or contributing a translation? Contact us.

Why dragons?

Breeding virtual dragons is all in a day’s work in biology classrooms using Geniverse, our free, web-based genetics software. Although Geniverse is a game-like environment, it’s far more than child’s play. Indeed, students dive into genetics on a quest to heal a beloved dragon. Students use a model species (drakes) to explore the fundamental mechanisms of heredity and genetic diseases and get a taste of careers in genetics. (Drakes are essentially a smaller version of a dragon, and are a model species in much the same way as the mouse is a model species for human genetic disease.)

But why did we choose dragons and drakes? To start, they are just plain fun! And since they’re mythical, we can bring together into one animal any and all real-world genes we’d like to teach with—without having to be restricted to a specific species’ genome. So, while our dragons and drakes are fantastical, their genes are very much real, gathered from mice, fruit flies, lizards, and other organisms we study in laboratories all over the world. When students learn genetics with Geniverse, they’ll encounter the genes again, should they venture into a real genetics lab later in life.

Students begin their Geniverse adventure as a student in the Drake Breeder’s Guild, where they move through four levels of progressively more difficult genetics challenges and unlock new chapters of the narrative. Try Geniverse now and learn how fun (and educational) dragons can be!

The real genes of Geniverse

Did you know that while dragons and their model species drakes are fictional and fanciful, the genetics of these virtual Geniverse creatures is based firmly on the real-world genetics of model organisms?

The drake genes and traits have been carefully compiled from the actual genes and associated traits of the anole lizard, mouse, fruit fly, zebrafish, and other model species. The genes for forelimbs, wings, color, and other drake traits are genes that are involved in the development of those traits in real organisms. There’s real biology behind the Geniverse narrative as well: the disease that plagues our hero’s dragon friend is modeled on a rare human metabolic disorder, ornithine transcarbamylase (OTC) deficiency. In fact, since the genes of humans are similar to the genes of the model organisms we use in real life—that’s why we can learn so much about human genetics from them—the genes of the Geniverse drakes are quite similar to human genes.

In addition, the interactive models that students use to conduct virtual experiments in Geniverse are powered by genetics programming that accurately simulates real-life patterns of inheritance in humans as well as model organisms. Students who learn with Geniverse are learning to analyze experimental results that would be obtained from these genes in a laboratory.

Nomenclature Genomic Location
Symbol w Chromosome 1
Name wingless Linkage map 70 cM
Species Dracomimus familiaris Genome coordinates unknown

 

Summary information
Phenotype: The wingless gene affects wing development in drakes. Homozygotes for the wingless allele (w/w) lack externally visible wings entirely. The skeleton of wingless drakes has a vestigial dorsal shoulder and a remnant of the proximal wing bone. Note: This gene and phenotype are taken from the fruit fly, d. Melanogaster, and the human correlate gene, called Wnt1, is 80% similar to the wingless DNA sequence.
   
W/W or W/w w/w

 

Alleles and Phenotypes
Allele Summary
W Presumptive wild-type allele
w Recessive allele
Genotype Phenotype
W/W Normal wings
W/w Normal wings
w/w wingless

 

Nomenclature Genomic Location
Symbol Wnt1 Chromosome 1
Name Proto-oncogene Wnt-1 Linkage map unknown
Species Dracomimus familiaris Genome Coordinates 1: 70 Mbp

At the University of Massachusetts at Amherst, students are utilizing bioinformatics tools to build new drake genes, mutant alleles, and phenotypes based on investigations of the scientific literature. In an exploration of multiple genetic mechanisms, students have created drakes whose genotypes give rise to deafness and dwarfism, cancer and cold tolerance, polydactyly, and the ability to spit spider silk. We’re thrilled to see these additions to our drake genome!

Designing panda solar power plants with Energy3D

Fig. 1: Panda power in Energy3D
Fig. 2: Panda power in Energy3D
A Panda-shaped photovoltaic (PV) solar power plant in Datong, China recently came online and quickly went viral in the news. While solar power plants in cute shapes are not a new thing (I blogged about the Mickey Mouse-shaped solar farm in Orlando, FL about six weeks ago), this one drew a lot of attentions because the company that built it, Panda Green Energy Group, is reportedly planning to build 100 more such plants around the world to advertise for renewable energy. According to the company's website, the idea of building Panda-shaped solar power plants originated from Ada Li, a student from Oregon Episcopal School. Li proposed her idea at the COP21 Conference in Paris.

The construction of the 100 MW Datong Panda Solar Power Plant began on November 20, 2016. It is expected to generate 3.2 billion KWh in a life span of 25 years. The plant consists of two types of solar panels of different colors: black monocrystalline solar panels and white thin-film solar panels. The two types form the characteristic shape and pattern of a giant panda, the national treasure of China and the logo of the World Wildlife Fund. Considering the number of people who complain about solar power plants being eyesores in their neighborhoods, these attempts by the Panda and Micky Mouse solar farms and their future cousins may provide examples to mitigate these negative perceptions.

Fig. 3: A close-up view of Panda power.
Fig. 4: A close-up view of Panda power.
One of our summer interns, Maya Haigis, who is a student from the University of Rochester, spent a couple of hours to create an Energy3D model of the Datong Panda Solar Power Plant after I shared the news with her today. The power plant is so new that Google Maps currently show only a picture of it under construction. So Maya went ahead to draw the power plant based on an artist's imagination taken from the news. Her design ended up using about 34,000 solar panels. To make it look like a real giant panda with its trademark black and white fur, I had to quickly add a light gray color option for solar panels in Energy3D. Maya's work came out to be amazingly realistic (Figures 1 and 2). This is even more remarkable considering that Maya had no prior experience with Energy3D.

Panda Green Energy said in the press release that they designed the power plant also for the purpose of engaging youth to join the renewable energy revolution. They are planning to reach out to schools for student site visits. There is also a plan to make the power plant a tourist attraction. I am not sure people would pay to go there to see it. But with Energy3D, we can imagine the experience by taking a virtual tour with the 3D model (Figures 3 and 4). The engineers among us can run Energy3D simulations to analyze its performance and investigate whether such an effort makes scientific sense.

So what about inviting children all over the world to "paint" the brownfields that have scarred our planet with this kind of good-looking solar power plants using Energy3D as a "solar brush?" Welcome to our Solarize Your World Initiative!

Remembering Robert F. Tinker

Concord Consortium Senior Research Scientist Sherry Hsi remembers our founder Bob Tinker who passed away on June 21st. For more personal stories about Bob and his impact, and to share your own, visit rememberingbob.concord.org

Barbara, Bob, and Sherry

The Concord Consortium East Coast Office – Me, Bob Tinker, and Barbara Tinker, August 2016

There are few times in the world when you can say you met a person who has changed your life. I’ve had the benefit of many wonderful mentors in my life, but Bob Tinker was the mentor who was my academic non-academia father. In 1996, I was in graduate school at UC Berkeley when I first met Bob. Marcia Linn brought me to SRI International where Roy Pea was convening different stakeholders to share the possible formation of a center for innovative learning technologies. Bob was so enthusiastic and energetic about ideas. Unlike others in the room, Bob wasn’t wearing a suit or tie. He was wearing a vest adorned with buttons, one of which read “Go VHS!” (for Virtual High School). He looked more like an activist. He was fighting for social justice, equal opportunity, and science education.

Bob invited me to visit the Concord Consortium shortly after the nonprofit opened on 37 Thoreau Street in Concord, Massachusetts. This is where I first met Ray Rose, Sarah Haavind, Bruce Droste, Carolyn Staudt, George Collison, and other education technology thought leaders. Netscape Navigator was two years old, yet the team was already implementing a model international online STEM professional development program for teachers and architecting the first virtual high school.

That was just the beginning of a wonderful adventure and mentorship. Bob and I would chat about crazy ideas like putting wireless cameras on birds and nestboxes, using mobile devices for citizen science, or designing smart museum exhibits that would be aware and responsive to visitor interactions. He would share with me drafts of how an idea – always in his signature blue Palatino font – would be iteratively shaped into a winning proposal. He showed how the most daunting and intimidating problems could be made accessible if you were willing to go back to core ideas, build models, and tinker a while without the fear of failure.

During my postdoc with the Concord Consortium and the Center for Innovative Learning Technologies, we explored ways to design and scaffold science inquiry using probes and handhelds in creeks and watersheds. We also sparked and seeded projects to grow the capacity of educational mobile STEM designers by hosting a design competition at the Exploratorium. (The winning app simulated the results of cross-breeding different fish on Palm Pilots.) Bob joined remotely to the live webcast by telephone. I remember how his super amplified voice boomed over the audience like a television voice from God, enthusiastic about the potential that collaborative learning and mobile devices could have on education.

Bob was the reason I left K-12 classroom research to work at the Exploratorium. He spent a few weeks of of the year in 1998 as an Osher Fellow when the museum was led by Goery Delacote, fellow physicist. He contributed to ideas during the formation of the Center for Media and Communication where I subsequently accepted a research position. He and Rob Semper asked what-if questions around the possibility of supporting deeper visitor engagement within the museum and extended science learning beyond. What if the whole museum had ubiquitous wireless access and fast networks for media sharing? Imagine that when 802.11b was new! This led to the Electronic Guidebook Project and a strand of early experiments to test inquiry using handhelds, RFID, cameras, and beacons with exhibits. Today, this pioneering work continues to re-emerge in different forms across many museums.

Bob was more than an academic mentor. He and his wife Barbara invited me into their home, lifted my spirits when life got tough, and pushed me back out into the world. Our most recent collaboration was working together on an NSF-funded project to bring Internet-of-Thing sensors and actuators into laboratories for high school biology to support science and engineering practices together with computational thinking. This brought me back to the Concord Consortium, but this time, in the West Coast office. Unlike when we first met, high-speed multi-site web video conferencing was now possible with a single click. The Maker movement now gave us so many low-cost DIY options to play with. We spent the last year connecting and chatting by Zoom from his workshop in Amherst.

I will miss his chortling, his outbursts about Reagan, his spreadsheet genius, his photography of nature, and his genuine care in all people. I enjoyed chasing ideas and money together, but my favorite memories are seeing him race down Pier 15 with my youngest son Lucas to see fog appear, hearing him hum and wash the dishes while Barbara and I played Schubert after dinner in Carlisle, and sneaking out of a PI meeting for a moment to watch a rainbow form right after a rain shower. He was always willing to share the last piece of toffee or ask for two spoons when he ordered dessert.

Bob – wherever you are, I hope you are flying high. Thanks for helping me grow. You gave me so many gifts and words of encouragement along the way. I feel lucky that our paths crossed in this large chaotic universe. You are one of a kind. I miss you terribly.

VHS Faculty

VHS online faculty: Bob McLean, Ray Rose, Bruce Droste, Me, Sarah Haavind and others waiting to meet Senator John Kerry October 1997.

Exploratorium Palace

Bob Tinker with Bernard Osher and Sally Duensing at the Exploratorium Palace of Fine Arts in 1998. Photo credit: Ron Hipschmann

Center for Innovative Learning Technologies

Center for Innovative Learning Technologies created in 1997. Slide credit: Roy Pea

Center for Innovative Learning Technologies

Center for Innovative Learning Technologies created in 1997.

Barbara and Bob Tinker

My academic non-academia parents Barbara and Bob Tinker at Aaron’s wedding in 2006.

Handheld Design Awards for Education

Live webcast of the Handheld Design Awards for Education at the Exploratorium, San Francisco Palace of Fine Arts, 1999.

Judging and handheld demonstrations at the Exploratorium in 1999

Judging and handheld demonstrations at the Exploratorium in 1999. Left: Phil Vahey, Justin Manus, Jeff Hawkins, Me; Right: Stephen Bannasch and Carolyn Staudt demoing probeware from the Concord Consortium

Marcia Linn and Bob Tinker

Marcia Linn and Bob Tinker at a Technology-Enhanced Learning in Science (TELS) event, Washington, D.C.

A typical web video conference

A typical web video conference when collaboratively working through hard problems together – Robert Tinker, Me, Hee-Sun Lee, and Chad Dorsey – October, 2016.

Bob Tinker at the March for Science

Bob Tinker at the March for Science in Amherst, MA – April 22, 2017. Photo credit: Barbara Tinker