I am a lecturer at the University of Tasmania and my videos are educational content about how the body works and how this goes wrong in disease. I am also a researcher investigating the innate immune system with a particular focus on how inflammation can contribute to disease.
Research projects
How do microplastics affect human health and the health of wildlife?
How does inflammation contribute to Alzheimer’s disease?
Developing novel drugs or re-purposing existing drugs to fight inflammatory disease.
How does the body control the inflammatory response?
If you are a national or international student interested in doing an Honours, Masters or Ph.D. research project on any of these topics please send an email to jack.auty@UTAS.edu.au for more information.
Could you not (in theory) still use slices of potato if you wanted to do, for example, mycological mycelium culture? I know that there would be no benefit, but I wonder if you lightly steam-sterilized the potato, then under a flow hood you carefully cut away the outer "cooked/steamed layer of the potato, then put thinly sliced sections of potato into petri dishes, would that work as a culture medium? I suspect that the interior of the potato (if fresh and skin intact) is free of contaminants (otherwise it would rot straightaway). So long as contaminants aren't introduced in the preparation, I think it might work...
How does the virus get into the phagosome of a macrophage? I though the macrophage will engulf the virus, if it can attach to some molecule on the virus surface. What is the macrophage attaching to on the virus surface?
I read that anterior eye is immune privileged now does that mean that the anterior eye proteins are never shown to maturing T cells in the thymus ?? Or cells are negatively selected in thymus but some cells which escape the negative selection may then get into eye following trauma and Damage the eye Another thing I read somewhere, injury to one eye can make another eye susceptible to activity of immune cells how is that so if the immune cells can not reach eye ?
I am studying the chi-squared goodness of fit hypothesis test to compare a histogram of a set of samples to the normal distribution with some mean and standard deviation. Some literature says that to calculate the amount of degrees of freedom we must use the expression: n_of_bars_of_histogram -1 - n_of_parameters. If I understand your explanation well, in the expression of the literature the parameters will take out 2 degrees of freedom and there is a number which cannot vary given some mean and standard deviation. Is this correct?
Hi there, you're a bit turned around. Phase contrast changes the phase of the non-diffracted (surrounding) light, not the diffracted light passing through the tissue. This light passing through the tissue has already been (-λ/4) phase-shifted by virtue of passing through the sample. The area you're depicting as the openings on the phase plate is actually a ring of material that changes the phase by either advancing background light by λ/4 (positive phase contrast) or retarding it by -λ/4 (negative phase contrast) in order to cause interference. It is not the middle of the plate as you show... that part just lets the diffracted light through. Light coming from the annulus ring and being focused into the phase plate ring has not been diffracted by the sample. The phase plate then makes the light out of phase (with the diffracted light, reducing the amplitude after it converges. That's why nuclei are really dark compared to the medium: there are a lot more diffracted waves that interfere with the background light significantly more than the medium. So just to clarify it is not how you show it, that the diffracted, phase-shifted light is being further phase-shifted. This would work poorly because the diffracted light passing through the specimen already has a low amplitude. Changing the phase of this light by passing it through another material would lower the amplitude again and actually reduce the contrast because the background light would flood the image.
We are both right, but you are focusing on a different effect of the phase contrast which explains why the nucleus is dark. Because phase contrast is not really used to look for nuclei and is mostly used for cell counting and cell morphology, I focused on the bright halo we see around the membrane. This is because of phase shifted and diffracted light causing positive interference. In this paper, this phenomenon is called D-leak. www.ncbi.nlm.nih.gov/pmc/articles/PMC3372640/
Oh I think I get what you are saying! Yeah we are saying the exact same thing. I wondered what you meant by "advanced". Glass doesn't advance a wavelength. It does the opposite. But I do see that Zeisus describes it your way too. The phase ring is actually a thinner piece of glass, while the body is a thicker piece of glass. So you could say that the thin glass ring advances the wavelength (+lambda/4) relative to the thicker glass of the body of the phase plate, or you could say that the body retards the wavelength relative to the light that passes through the ring (-lambda x 3/4) . The important thing is that these perturb the wave timing differently to eachother. Glass cannot "let diffracted light through". Glass will always effect the wave timing. So it is all about relative effects of the different thicknesses of the glass. In my mind thinner equal less purturbed makes sense. I did also leave out that the phase ring normally dims the light with a metal layer.
If europeans treat asylum seekers as people why are many countries now denying them? Seems like this leftist attitude had changed since this video was originally published. Was getting a lot out of this video until you started injecting politics into it
Your video Is best I have found on RU-vid for the principle of phase contrast I will recommend it to my colleagues thumbs up for the graphic dedication you put but you didn't put the ocular lens in most diagram
Somewhat disappointing that Jack does not mention that the alpha secretase pathway is actually promoting neuroplasticity while the beta amyloid pathway which is traditionally thought of as pathogenic is also physiologically recruited for synaptic pruning, and for immune defense.
Superb review. I've been listening to reviews on inflammation in Alzheimer's disease for decades. This is one of the best overviews. First rate and intelligible
Love to know how this information can help people with Autoimmune? So many people suffer and all that’s available are drugs with loads of side effects that suppress the whole immune system. Please make another video if your aware of available treatments that have been successful.
