What is a time-space scale version of KdV equation?

09 October 2014 6,025 0 View

If sin(a sk)/a= sin(b sk)/b for the sequence sk\to infty as k \to infty for some a not equal to b, then a/b is rational and sk=2k pi/b? Is it true?

For particular case b=2a we have sin(2b sk)/(2b)= sin(b sk)/b which yields cos(b sk)=1 or sk=2k pi/b. It is true also if the sequence sk that approaches infinity as k approaches infinity is...

31 December 2013 1,229 4 View

Are there unbounded solutions of (1-cos(x pi))/x-(1-cos(y pi))/y+(1-cos((x-y)pi))/(x-y)=0 but with even integers?

The sequence x=2k y=2n where k and n are natural numbers solves this equation. Is there any other unbounded sequence of solutions?

11 December 2013 3,637 7 View

Quadratic equation (complex coefficients) have roots with equal real parts if and only if discriminant is real, non-positive. What about quartic?

z^2-(2+3i)z+3i-1=0 has discriminant=-1, roots (1+i) and (1+2i) have equal real parts. Find a similar statement for the quartic equation: z^4+az^2+bz+c=0.

10 November 2013 2,425 8 View

2 roots of x^3+6a x+2b=0 where a, b are complex have the equal real parts if a, b are real and discriminant is non-positive. Is it true?

For the quadratic equations with complex coefficients 2 roots have the equal real parts if and only if the discriminant is nonpositive.

07 August 2013 2,957 4 View

e^(z_1)+e^(z_2)=0 if and only if Re(z_1)=Re(z_2) and Im(z_2-z_1)=pi(2n+1), where z_1, z_2 are complex numbers. Is there a similar statement for the sum of 4 exponents e^(z_1)+e^(z_2)+e^(z_3)+e^(z_4)=0 ?

This question is connected with the oscillations of differential equations. Since every solution of the linear equation with constant coefficients is the linear combination of exponents this...

04 May 2013 2,279 51 View

Mobius transformation maps arcs of circles to arcs of circles. Is there similar geometric property for the quotient of quadratic functions?

The quotient of linear functions with complex variable z (Mobius transformation) maps arcs of circles to arcs of circles. Is there similar geometric meaning for the quotient of quadratic functions...

01 January 1970 4,132 3 View

How to compare two groups with only two measurements?

Hiiiii everyone! I have an enquiry on statistical analysis. I was looking for many forum and it's still cannot solve my problem. I want to compare means of two groups of data but only with two...

03 March 2021 8,796 3 View

Enhanced Yellow Fluorescent Protein (Aequorea victoria) DNA sequence?

I am on the lookout for the Enhanced Yellow Fluorescent Protein (Aequorea victoria) DNA sequence. Does anyone know where I can find it? Thank you in advance

03 March 2021 3,568 1 View

What kind of fluid could I use for a pitfall trap that also does not invalidate molecular testing?

Hi, I want to start testing pitfall trap to obtain ants samples, but I need to conduct molecular analysis on those insects. So, what kind of fluid can I use? Ethanol expires too early and I need...

03 March 2021 5,978 5 View

What's the best way to measure growth rates in House sparrow chicks from day 2 to day 10?

What's the best way to measure growth rates in House sparrow chicks from day 2 to day 10? Since, the growth curve from day 2 to 10 won't be like the "Logistic curve" it might not follow logistic...

03 March 2021 1,401 3 View

Do we need to write protocol for a second study of a systematic review that has been registered and published?

I have conducted and published a systematic review and meta-analysis research with the topic related to public health and health pomotion (protocol was registed in PROSPERO). Now we want to...

03 March 2021 8,920 3 View

How to increase a model accuracy ?

dear community, my model is based feature extraction from non stationary signals using discrete Wavelet Transform and then using statistical features then machine learning classifiers in order to...

03 March 2021 6,994 5 View

Do I need to do linear regression before running mediation analysis using PROCESS MACRO by Hayes ?

I just wanted to check if I need to run a linear regression separately if I am using PROCESS MACRO to run mediation analysis. Thank you.

02 March 2021 4,359 3 View

Sample dilution for quantitative analysis using ELISA?

If the detection range is in ng/ml but the reference range is in ug/ml for a molecule or protein in serum or plasma .how to dilute and what is the initial volume to be taken for quantitative analysis

02 March 2021 7,670 3 View

Is There Any Feasible Method To Test Fluorescent Compounds Other Than Fluorescence Spectrometers ??

Is There Any Feasible Method To Test The Efficiency Of Fluorescent Compounds Other Than UV Spectrometers ? Suggestions Would Be Appreciated !

02 March 2021 5,785 3 View

How to calculate average trend in maximum annual NDVI from MODIS?

I am wanting to calculate the average trend in maximum annual NDVI in Iceland from 2010-2020 using MODIS MYD13Q1 V6. How would I do this? I have currently inserted the NDVI bands from the MODIS...

02 March 2021 752 2 View