Recent content by stephenx_86

The distribution of Z-scores does indeed follow a normal distribution; one that appears to follow the distribution predicted by the Z-score calculation (probability as a function of deviation from the expected value). I've spent the last few days further reading relevant papers and it's...

The distribution we're observing is generated by individual fluorophores binding to a microscope slide. Since the size of the fluorophores (diameter ~25 nm) is much less than the average distance to the nearest neighbour (~2 μm) we're assuming it to be negligible (i.e. no spatial restriction)...

Thank you both for your responses. The data is indeed intended (hopefully) for publication, so if an alternative approach entirely is required I'll be happy to read into it. This Bayesian statistical approach sounds promising. Although I've been using CrimeStat to analyse the...

Hi, My apologies; I've not done any in depth statistics before and wasn't aware of what are common terms. I'll try and explain the problem, but please let me know if I need to clarify terms further. What I've got is a distribution of points in two dimensions; it's expected these will show...

Hi, I've got a distribution of points in two dimensions and would like to demonstrate if these are randomly distributed. The points have been measured using single particle tracking, so likely have some degree of error in their position. What I'd like to show is whether, as time progresses...

Meaning of "% fs" Hi, We're using a lock-in amplifier to oscillate an AFM-style cantilever (across a frequency sweep) and measure the response using a QPD. The aim of this is to see how the resonant frequency changes with changing environmental conditions. The software we use...

Hi, Thank you all once again for these useful responses. We've got a low concentration of fluorophore and intend to see small populations (each protein will be tagged with a single fluorophore, but may get tens of proteins bind together). We're not intending to photobleach the sample...

Thank you both for your replies. The objective is a 60x Olympus UPlanSApo lens, which has a numerical aperture of 1.35. We wish to excite relatively small numbers of fluorophores within the imaged region. Just to clarify, would focussing the laser at the back pupil plane achieve a diverging...

Hi, I'm trying to set up a microscope to have wide-field laser epi-illumination. This is to be used with an infinity-focused objective lens. My current plan has the laser expanded 4x using a Galilean beam expander (from 1mm to 4mm) and coupled into the back of the objective using a...

That's brilliant, thanks for your help.

Hi, (To cut a long story short, can I cancel the integrals in Eq. 6 to leave me with Eq. 7?) I am trying to follow the method for modelling the motion of a tethered bead from a couple of papers ("Te Velthuis, A. J. W. et al. (2010) Biophys. J. 99 1292–1302" and "Lansdorp, B. M., & Saleh, O...

Thank you both for your replies, I now understand what is happening. It seems I had a fundamental misunderstanding regarding the objective lens - I thought the distance from the objective lens to the sample was always at the "working distance". What you have said now makes sense in terms of...

Hi, I was hoping someone would be able to help me with a microscopy problem that has been puzzling me for a while. I'm building a basic microscope from scratch using a 50x long working distance Nikon objective (LU Plan ELWD, wd = 10.1mm, NA = 0.55). The sample is illuminated from above using...

Hi, I'm making laminar fluid flow devices and want to be able to calculate the velocity as a function of distance from the channel edges. As the channels are relatively wide compared to their height I'm treating the effect of the parabolic velocity profile as negligible in the horizontal...