Selecting particular columns from large datasets (csv) using R Studio?

So I have large number of csv files (100+) in a directory with same structure and column names. The data is in time series and there are approx 30 columns/file. However i only want to aggregate...

08 February 2021 245 5 View

How much pre-PCR dilution of mixed-template DNA extracted from pollen (honey) is appropriate for Metabarcoding?

I'm working on pollen DNA metabarcoding to identify the floral composition of honey. How much pre-PCR dilution of mixed-template DNA extracted from pollen (honey) is appropriate for the...

28 December 2020 9,132 1 View

How to add two vertical and parallel Fresnel reflection coefficients to retrieve overall reflection coefficient for a right hand circular wave?

I have a problem in which a right hand circular polarized wave (GPS wave) encounters an ideal smooth plane obliquely, and then is reflected off that. To solve this kind of problems, the wave is...

28 December 2020 2,271 3 View

Which is better to focus on teaching or research for a good academic life and Why?

Which is better to focus on teaching or research for For a good academic life and Why?

26 December 2020 5,737 9 View

Is ag paste suitable for back contact on silicon wafer? or i should deposit al on the back surface using pvd or plasma sputtering?

Fabricating silicon solar cell

22 December 2020 4,906 7 View

Which renewable source is the best ?

wind hydro solar etc.

21 December 2020 6,360 16 View

Why is light pure energy?

light is pure because the light is the simplest electromagnetic construct but the energy of any object is also of the same kind.

20 December 2020 207 4 View

How to handle Missing Values for Skipped Questions (Systematic Missing) in R ?

10 December 2020 435 4 View

What is the best industrial emulsifier to make silicon oil in water emulsion?

I need to make long-lasting stable emulsions of 6 wt. % percent silicon oil in DI water. The previousely made emulsions using Tween and Span Emulsifiers did not remain stable after a week.

31 October 2020 3,568 3 View

Carbon Emission calculation factors ?

I am thinking about writing a paper on carbon emissions based on electricity consumption data from some buildings. From a research perspective, which factors should i specially focus while...

09 October 2020 4,142 3 View

Physics: Why do we describe light by referring to its wavelength, but microwaves and radar pulses by referring to their frequency?

In physics, the description of the properties of light generally refers to its wavelength (nm), while in the range of microwaves and radio waves we refer to the frequency of a signal (e.g. kHz or...

03 March 2021 1,682 3 View

Why are the velocities so high in my Boussinesq approximation Fluent simulation?

Hello, I have a mechanism where air rises due to convective flows. In this simulation, nothing is driving the air except this. I understand that the Boussinesq approximation only works for small...

02 March 2021 4,910 3 View

Why almost every element would be metallized in sufficiently high pressure and low temperature?

(This statement is from wikipedia, BTW). What is so special about metallic bond that is limiting high-P low-T state of a matter (as long as individual atoms exist, not white dwarf of neutron star...

02 March 2021 3,309 2 View

New Journal, "Integrative Psychological and Behavioral Science" -- do you not know, and have you not seen, this done before?

Question to you and THEM, the New Journal, "Integrative Psychological and Behavioral Science" -- do you not know, and have you not seen, this done before? There appears to be a core problem for...

02 March 2021 3,024 2 View

Which SAR dataset to use for generating coherency matrix and performing target decomposition (Description) ?

Working on chandrayaan-2 DFSAR data, there are three datasets available: 1) Slant range image data product: The slant range complex image file. Each pixel is represented by two 4-byte floating...

02 March 2021 8,481 3 View

Which is a lucid standard comprehensive book to guide on psychological scale construction and its standardization?

02 March 2021 7,082 3 View

LOAD DISPLACEMENT CURVES Stiffness increasing in ANSYS non linear analysis. HOW CAN I CORRECT IT?

Hi. I am doing non linear FE analysis using a new material beam under flexural 2 point loading using ANSYS. I have defined a bilinear material model. The solution has converged. In results I am...

01 March 2021 9,911 3 View

Can we distinguish the type of free fluid inside the pelvic and abdominal cavities whether blood or serous fluid using the ultrasound?

during ultrasound examination of acute abdomen, sometimes we see free fluid , can we know the type of fluid ,whether blood or not , using ultrasound only? if yes , what are the sonographic...

01 March 2021 7,476 4 View

How to choose ANN number of hidden layers and nodes?

Hello, Could you please share any interesting research explaining how to choose the number of hidden layers and nodes per layer in case of regression problems using ANN? Thank you, any help would...

01 March 2021 6,200 3 View

What is the density for pva electrospining?

I'm Juan Carlos, a high school student who is working with electropinning, I made an electropinning machine with a 21g needle and a 30kv high voltage source and the distance between my needle is...

28 February 2021 298 3 View