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Researchers at Linköping University’s Department of Thematic Studies, Environmental Change, have developed a simple logger for greenhouse gas flows. It is built using inexpensive and easily available parts, and provides data on levels of methane, carbon dioxide, temperature and humidity.

Make your own greenhouse gas logger

Methane logger built by using inexpensive and easily available parts. Image credit: Linköping University

“So far, measurement instruments have been so expensive that society’s mapping of greenhouse gas emissions has had to rely on rough models. It’s extremely important that we can make lots of proper measurements locally, so we can test whether measures for reducing emissions actually work. We hope that our simple and cost-efficient logger can contribute to more such measurements”, says David Bastviken, professor at Environmental Change, and author of an article in Biogeosciences.

Lack of low-cost measurement methods

A current limitation when it comes to determining the greenhouse gas fluxes has been the lack of reliable low-cost measurement methods that can be widely available in society. In 2015, David Bastviken and colleagues described and published a logger for carbon dioxide, which is now used for various types of environmental measurements. However for methane, more complicated and expensive measurement equipment has so far been required. In the current article in Biogeosciences, the researchers describe an inexpensive sensor for methane.

Methane, CH4, is one of the most important long-lived greenhouse gases which contributes greatly to global warming. Since the 1750s, its relative increase in the atmosphere has been greater than for other greenhouse gases. There are many different sources and examples including incomplete combustion, handling of natural gas and biogas, and microbial production in agriculture, wetlands and lakes. However the large number of sources that can vary greatly in ways not fully understood makes it difficult to quantify fluxes and to propose best practices for flux mitigation. In addition, the discovery that lakes, rivers and flooded forests are large sources of methane, made by David Bastviken and his colleagues as recently as 2011 and later, shows that major methane sources are still being discovered.

Open-source hardware

“We have now built and tested a simple logger based on the open-source Arduino hardware. The parts are available in many electronics stores; they can be ordered online and cost about 200 euro. We have also developed more precise ways to calibrate the methane sensor, to enable the measurement of greenhouse gas fluxes at a very low cost”, says David Bastviken.

The researchers hope that the logger will make it easier for all interested, and in e.g. education and environmental monitoring, to monitor greenhouse gas emissions.

“We also propose simplified but satisfactory ways to calibrate the sensors that don’t require continuous access to advanced research laboratories. This can make measurements easier, for instance in developing countries”, says David Bastviken.

Building instructions

Complete instructions for building a logger, and various calibration methods, can be found in the article and in accompanying extra materials, which are freely accessible via Biogeosciences.

The study was funded by the European Research Council (ERC), the Swedish Research Council and Formas.

Bastviken, D., Nygren, J., Schenk, J., Parellada Massana, R., and Duc, N. T.: Technical note: Facilitating the use of low-cost methane (CH4) sensors in flux chambers – calibration, data processing, and an open-source make-it-yourself logger, Biogeosciences, 17, 3659–3667., 2020.

Written by Monica Westman Svenselius, Translated by Martin Mirko

Source: Linköping University

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How to copy expressions without changing cell references in Excel

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Microsoft Excel updates cell references when you copy an expression. Here are a couple of workarounds for those rare occasions when you don’t want to change the cell references.

Image: AndreyPopov, Getty Images/iStockphoto

Microsoft Excel has a helpful behavior in regard to copying expressions. After entering a row or column of expressions, you can copy them, and Excel will update the cell references according. Otherwise, you’d have to enter all expressions manually and that would be tedious and open to error. However, it’s not uncommon to run up against a situation when you won’t want to update the references. There’s no easy built-in way to do this. In this article, I’ll show you two quick workarounds for copying expressions without updating the cell references.

SEE: 60 Excel tips every user should master (TechRepublic)

I’m using Microsoft 365 on a Window 64-bit system, but this works in older versions. You can work with your own data or download the demonstration .xls file. Both methods work in the browser. 

How copy works with expressions in Excel

When you copy an expression by using the fill handle, Excel updates relative cell references. For instance, if you copy the simple expression =B3/C3 one cell to the right, Excel will adjust the column reference and enter the expression =C3/D3. If the column reference is absolute ($), Excel will change nothing, and copy =$B3/$C3. However, if you copy the expression down one row, Excel will update the row reference because it isn’t absolute: =$B4/$C4. The same behavior is in play whether you use Ctrl+C to copy the expression or move it. This behavior makes it difficult—impossible—to copy an expression when you don’t want to update the cell references unless all of those references are absolute: =$B$3/$C$3. 

SEE: TechRepublic Premium editorial calendar: IT policies, checklists, toolkits, and research for download (TechRepublic Premium)

The easy way handles a single expression in Excel

If you have only a few expressions to copy, retaining the original references, you can use the formula bar in edit mode. It’s quick, easy and gets the job done. We can illustrate this using the simple data set shown in Figure A as follows:

  1. Select D3.
  2. Go to the formula bar and highlight the entire expression.
  3. Press Ctrl+C.
  4. Press Esc.
  5. Select the destination cell, F3, and press Ctrl+V.

As you can see in the data set to the right in Figure A, both expressions reference the same cells, B3 and C3. If you’re working in the browser, you’ll need to erase the ‘ character in the destination cell before it will evaluate the expression.

Figure A


  Let’s copy the expressions in column D without updating the cell references. 

This method is quick and easy but works with one or a few expressions. If you have a lot of expressions, this method will take a long time. Now, let’s look at a second method that takes a bit more work but works with lots of expressions simultaneously.

The hard way handles many expressions in Excel

If you want to make the same change to several instances of the same content, what tool do you usually use? Replace—that’s right! That’s the tool we’re going to use to copy many expressions without changing the cell references at the same time:

  • First, we’ll add a special character to the beginning of selected expressions using = as the Find string and # as the replace string Excel will treat the expressions as text 
  • Then, we’ll copy the expressions to the new destination.
  • Finally, we’ll replace the special character we used in step 1 with the = character.

SEE: How to expose expressions that return a defined error value in Microsoft Excel (TechRepublic)

Now, let’s run through a quick example using the expressions in column D:

  1. Select D3:D8.
  2. Press Ctrl+h or choose Replace from the Find & Select dropdown in the Editing group (on the Home tab)
  3. Enter = in the Find what control.
  4. Enter # in the Replace with control (Figure B). You don’t have to use #; you can use most any other character but use one that’s not in use or you might get unexpected results. That’s why I chose #. If # is in use, come up with another character or even a string of characters, such as AAA or ZZZ.
  5. Click Replace All.
  6. Click OK to confirm and Close.

As you can see in Figure C, Excel treats all of the selected expressions as text.

Figure B


  Enter the find and replace characters.

Figure C


  Excel displays the expressions as text.

Using your favorite copy and paste method, copy the contents of D3:D8 to F3:F8. Now, it’s time to replace the # character with the = character. To do so, repeat the above instructions, but in step 3, enter # and in step 4, enter =, reversing the original search strings. When you’re done, you will have matching expressions in columns D and F (Figure D). You can select both sets by creating a non-contiguous selection or you can run the Replace task twice.

Figure D


  With a few easy steps, you copied a selection of expressions without changing the cell references.

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A Human-Computer Duet System for Music Performance


Despite the popularity of virtual musicians, most of them cannot play together with human musicians following their tempo or create their own behaviors without the aid of human characters. The authors of a recent paper created a virtual violinist having these characteristics.

A Human Computer Duet System for Music Performance

Image credit: 刘睿忱 via Wikimedia (CC BY-SA 4.0)

It can track music and adapt to the human pianist’s tempo varying with time and with performance, making the two voices harmonized. The virtual musician’s body movements are generated directly from the music. The motion generator is trained on a music video dataset of violin performance and a pose sequence synchronized with live performance is generated.

These features mean that the human musician can practice, rehearse, and perform music with the virtual musician like with a real human, by following the music content. The proposed system has successfully performed in a ticket-selling concert, where a movement from Beethoven’s Spring Sonata was played. 

Virtual musicians have become a remarkable phenomenon in the contemporary multimedia arts. However, most of the virtual musicians nowadays have not been endowed with abilities to create their own behaviors, or to perform music with human musicians. In this paper, we firstly create a virtual violinist, who can collaborate with a human pianist to perform chamber music automatically without any intervention. The system incorporates the techniques from various fields, including real-time music tracking, pose estimation, and body movement generation. In our system, the virtual musician’s behavior is generated based on the given music audio alone, and such a system results in a low-cost, efficient and scalable way to produce human and virtual musicians’ co-performance. The proposed system has been validated in public concerts. Objective quality assessment approaches and possible ways to systematically improve the system are also discussed.