If you own the copyright to this book and it is wrongfully on our website, we offer a simple DMCA procedure to remove your content from our site. Start by pressing the button below! Quantum liquids: a review by P. Anderson Home Quantum liquids: a review by P. Ferreira If I were to pick one idea from modern physics that has seeped into popular culture, it would be the Heisenberg uncertainty principle. David Lindley rolls out a few choice examples toward the end of his new book, Uncertainty: Einstein, Heisenberg, Bohr, and the Struggle for the Soul of Science.
Because Lindley has done a pretty good job in sorting out the tangled ideas of quantum physics, his book just might lead the general public to understand what the principle is all about. Ferreira is a reader in physics at the University of Oxford in the UK. His interests are in cosmology, the early universe, the cosmic microwave background, and astroparticle physics.
Lindley tackles a similarly ubiquitous concept: entropy. He tells a compelling narrative of Ludwig Boltzmann and how the troubled physicist slowly came up with his view of statistical physics. His erratic career path in physics and his untimely death were a result of his lifelong battle with depression. The definition of entropy, the idea of irreversibility, and the birth of the quantum emerge from a life steeped in irrationality. The mix of emotion and high concept worked incredibly well.
In Uncertainty, Lindley tries the same approach, albeit on a grander scale. To faithfully narrate the development of quantum physics, he had to weave together the stories of numerous characters. Bohr plays a lead role.
Quantum liquids in confined geometries exhibit a large variety of new and interesting phenomena. For example, the internal structure of the liquid becomes more. Microscopic Approaches to Quantum Liquids in Confined Geometries [Eckhard Krotscheck, Jesus Navarro] on ykoketomel.ml *FREE* shipping on qualifying.
Einstein comes across as the cantankerous old uncle, overtaken by events and skeptical of the path modern physics is taking. For example, with Boris Podolsky and Nathan Rosen, he came up with a thought experiment that neatly showed some of the strange and, to him, unacceptable consequences of quantum mechanics: correlations of physical properties at spacelike separations. Uncertainty is a mess of ideas and characters, a compelling read. Lindley has successfully created an arc and has been careful not to overly systematize the events that flesh it out.
He has been able to profitably give us a real sense of the process of discovery in the early 20th century, as Europe hurtled toward war and the repression of intellectual life. Chaos was the essential background to the emergence of the quantum, the gem of modern physics. Editors, journalists, and scriptwriters should read the book before they cherry pick any more quantum concepts.
They will enjoy it and will look less foolish. Leggett Oxford U. Press, New York, Chapters are devoted to liquid helium-4, Bose—Einstein condensation BEC in cold atoms, classical superconductivity, liquid helium-3, and cuprate superconductivity; a final, eighth chapter covers August Physics Today 57 assorted exotic systems.
The early chapters of the book also divagate on a number of questions that seem out of place in a text at this level. For graduate students who want a thorough grounding in some of the most fundamental aspects of quantum fluids—such as statistical mechanics in a rotating container, the Landau—Silin approach to metals, the dynamical theory of the dielectric constant of metals, and the theory of Feshbach resonances in dilute gases—Quantum Liquids would be very useful. And for those of us who have specialized in a particular branch of the field and need updating on the marvelous things that have been done with cold atoms or on the beautiful details of the liquid 3He story, the book is a wonderfully informative source.
But from time to time it seems as if the author has distorted or ignored history. One wonders if Henry Hall and Joe Vinen would have been happy being dropped from the history of quantized 58 August Physics Today vorticity in superfluid 4He. In the chapter on classical superconductivity, John Rowell is not mentioned in connection with the Josephson effect. And perhaps I might have earned some credit for the formalism in section 5. In addition, the entire and crucially important subject of flux lattices, flux pinning, and creep and flow is postponed to a cursory inclusion in the chapter on cuprates.
The omission of the flux lattice and flow properties constitutes a serious incompleteness in a learning tool. For my specialty, the cuprates, I had hoped to see a thoughtful, if idiosyncratic, treatment like those in the previous chapters; instead, the coverage in chapter 7 does not actually reflect the modern state of the subject. Yet Leggett is not finicky about the mathematically questionable basis of the antiferromagnetic spin-fluctuation theory. Another example: A long-ago paper by one of his close colleagues, Myron Salomon, shows that the transition is always of x—y character—that is, into a fluctuating paired liquid—which invalidates the naive Jeff Tallon phase diagrams that Leggett uses.
In a few paragraphs in chapter 8, Leggett dismisses the large field of organic superconductors.
To the best of our knowledge, these have not been characterized before in amphioxus, and we believe may represent extracellular vesicles or exosomes Light sheet fluorescent images of marine animal embryos and larvae. Samples in figure a , c , d were stained with Alexa Fluor conjugated WGA, and the images were obtained directly with long exposure time to achieve the projection effect.
The sample in figure b was stained with SYTO 81, and the image was obtained by applying a maximum intensity projection to the image stack which contains individual sections. Image intensities are normalized, colour bar is shown. In our images of ascidian embryos, as in Fig. The monolayer test cells TCs which form the epithelial layer were clearly resolved.
Although the larva twitched its body, utilizing developed muscles to try to move beyond the trap, it was nevertheless confined in the trap throughout our LSFM experiment. Capturing such rapid movements demands high-speed imaging. Whilst acoustic trapping provides suitable force for the confinement of micro-organisms, we demonstrate that it can also suspend aquarium fish such as zebrafish larvae, with the presence of low-dose anaesthetics.
Currently, suspension of the specimen in LSFM is commonly achieved through the use of agarose gel. With acoustic trapping, the sample is held directly in the optimal medium, hence, drug delivery is straightforward. Responses of the heart rate were recorded before, during and after treatment with verapamil which is a calcium channel blocker used to treat high blood pressure and to decrease heart contraction.
The dynamics of the zebrafish heart were quantified using optical flow analysis see Methods. Optical flow analysis was used to map the local 2D displacement field in the heart between each consecutive frame i. The contraction of the ventricle can be seen from the convergence of the velocity vectors towards its centre. Similarly, the relaxation of the ventricle and the contraction of the atrium can be seen from the respective divergence and convergence of the velocity vectors, concentrated around certain regions of the heart.
To quantitatively profile, the mechanical deformation of the heart, the local volumetric strain rate was calculated from the estimated velocities Methods. The strain rate can be integrated across the entire set of images, producing the total volumetric strain, i. Normal ventricular contraction is significantly recovered after the removal of the drug. Verapamil also induced a slower heartbeat, as evidenced by the longer period in Fig. Velocity vector plot of the zebrafish heart estimated using optical flow analysis illustrating stages of the cardiac cycle: a contraction of the ventricle; b relaxation of the ventricle; c contraction of the atrium.
Time elapsed relative to the first frame is noted on the figures. Contractility mapping of the zebrafish heart. The three stages of this experiment are indicated by vertical lines in Fig.
Storing of hydrogen in metals, an important feature for the development of renewable energy sources. The text will be a useful reference for the biomolecular simulation community and help attract talented young students into this exciting frontier of research. Moroni, Bounds for the phonon-roton dispersion in superfluid 4He, Phys. Szybisz and I. Dynamics of atom scattering from 4 He nanoclusters. Giorgini, J.
During the first stage, a baseline heart rate was determined, prior to the introduction of verapamil. Clearly, in addition to the time required for drug delivery within the medium, time is also required for diffusion into the sample. At stage three, the active compound was washed away with fresh medium, and the heart rate partially recovered, although only one sample returned to its original rate. Six out of eight tested samples are shown in Fig.
Zebrafish heart rate and beat amplitude with the addition of drugs. Zebrafish heart rate change due to a verapamil and b norepinephrine, normalised to the resting rate. Contractile beat amplitude in the ventricle c and atrium d , upon addition of verapamil, presented as the total peak-to-peak amplitude of the volumetric strain. Each plot is presented as a mean value solid lines with error bounds of one standard deviation dashed lines across all results dotted lines. The drug is added at beginning of period ii , then washed away in period iii.
The heart rate and amplitude were recovered through Fourier analysis Methods. The data was averaged across central portions of the atrium and the ventricle. The beat amplitude follows a similar trend. The amplitude is normalised to the resting volume of the heart; however, there is significant variability between each animal.
With the removal of the drug, the amplitude partially recovered, still exhibiting significant inter-sample variability. Interestingly, the sensitivity of zebrafish to adrenergic agonists greatly increases in the early stages of development. For instance, the expression of adrenergic receptor genes in 3—4-dpf zebrafish can be 2-fold larger than in 2-dpf zebrafish Interestingly, following the expected decrease in heart rate from verapamil, in both experiments, after drug removal, the heart rate returned to the original levels observed prior to treatment.
This may be due to the lower verapamil concentration or increased drug resistance in these more mature samples compared to that of younger larvae. Such differences are likely due to a combination of variability in drug diffusion rates into the sample and differences in the pharmacological mechanisms for each drug.
At the end of the trapping experiment, the animal showed no aberrant behaviour except a slightly reduced heart rate which may be attributed to long-term exposure to tricaine. Taken together, these control experiments demonstrate that acoustic trapping in and of itself has little to no detrimental effect on the biological samples studied here, even after prolonged exposure.
Agarose is currently in widespread use as a method for embedding samples during imaging studies, in particular, those utilising LSFM; however, the means of physical trapping constrains potentially alters the development and physiology of the organism 1 , 2 , 3. Here, by integrating ultrasonic transducers into the sample chamber, we demonstrated contact-free suspension of the sample in optimum fluid. Compared to the use of optical forces, acoustic trapping is particularly advantageous for large samples, as stable confinement is achieved when the wavelength of the ultrasound is commensurate with the dimensions of the sample.
We have demonstrated trapping of samples ranging from hundreds of microns to several millimetres in diameter, utilizing MHz frequency transducers. If needed, lower frequency transducers could be utilized for even larger specimens. Our design for a sample chamber with integrated acoustic trapping capability is independent of the optical setup, meaning that such an arrangement can easily be retrofitted into other LSFM setups. The intensity of ultrasound required for trapping has been proven through a number of studies to cause little harm to biological samples.
Some of those tests were performed on organisms over relatively short exposure times 17 , 18 , 19 , 20 , whilst others were performed on mammalian cells with MPa ultrasound pressure over longer periods of time up to days 38 , 39 , Here, we have performed a long-term viability study with zebrafish larvae, as a step towards improving our understanding of the effects of long-term acoustic trapping upon a range of marine organisms. The maximum input voltage of 7.
This is in line with other long-term cell viability studies in the literature 39 , 40 , and the intensity is much less than that used for focused ultrasound therapy Our findings are that, even for prolonged acoustic exposures, no adverse effects have been observed. Although often small in size and transparent with good optical qualities, many marine embryos and larvae represent particular challenges for live imaging.
Premature removal of the chorion, prior to normal hatching, can affect the organisation of ectodermal cells or the expression of genes involved in left—right symmetry generation in ascidians 42 , Moreover, many embryos are covered by cilia e. Methods to immobilise these specimens for imaging require physical constraint, for example between glass coverslips, or by the application of compounds that may disrupt ciliary function—both of which can perturb normal development. Our results underscore the potential of acoustic trapping as a method with promise for longitudinal imaging of marine and other small aquatic embryos, particularly if combined with the use of fluorescent reporters and transgenic lines, or with the application of compounds, demonstrated here for zebrafish.
There is ample evidence that mechanical cues, such as physical confinement, can alter biological processes 1 , 2 , 3 , Rapid estimation of displacements from high-throughput dynamic images coupled with the high spatio-temporal resolution of LSFM can reveal a broad range of these mechanical processes Optical elastography, the imaging of tissue mechanics using optics, is an emerging technique The combination of sub-micrometre resolution and rapid imaging, to date, has been challenging to achieve, which may see LSFM emerge as an advantageous tool in this field.
We have demonstrated a straightforward design for fast imaging of samples through acoustic suspension and LSFM imaging. This dual-sided design may be more suitable for larger specimens. Here, we have reported the response of zebrafish larvae to verapamil, norepinephrine and high-dose tricaine, monitored via analysis of LSFM time-series data. This allows heat rate frequency and amplitude analysis. This experimental method enabled us to place clearer constraints upon the dynamic response of the specimen to the compounds applied.
Without the methods shown here, drug delivery is typically achieved by pumping the medium containing the drug compound into the sample chamber, which is filled with agarose or similar gel. In the absence of an embedding gel, fluid flow through the sample chamber and acoustic streaming effects may potentially aid standard diffusion, shortening required drug exposure times. The methods presented here should allow for the incorporation of further enhancements to drug delivery, offering still more precise timing measurements to be performed.
Elements of the optical portion of our light sheet setup were adapted from the previous work The beam was expanded and passed through an adjustable slit and a cylindrical lens to form a light sheet. To eliminate any effects that the imaging objective might have upon the acoustic field when translating the sample, the sample was kept stationary; instead, the light sheet and detection plane were scanned, in synchronized fashion 30 , Image stacks were constructed with open-source software FIJI For sample positioning, we created a counter-propagating dual-beam acoustic trap via two spherically-focused bowl-shaped transducers.
This commonly used piezoelectrically-hard piezoelectric material has a high Q value and is able to provide large power and force. This resulted in a f -number f of 0. The use of small f and high frequency also ensured a tight focus and high acoustic pressure at the focal point, leading to large pressure gradients and trapping forces near the trapping spot in the confocal system.
The confocal system formed a quasi-standing wave field, where the dense objects were acoustically moved away from energy density maxima pressure anti-node and trapped at the energy density minima pressure node. The likelihood of cavitation is largely suppressed by our selection of a MHz-range operating frequency 20 , hence avoiding damage of the biological samples. The active piezoelectric material was mounted into a stainless steel tube with mm inner diameter, then conductive silver epoxy was applied between the front surface of the active element and the metal tube for electrical grounding.
The transducers were air-backed to maximize the output power. Previous studies of acoustic traps with similar configuration have demonstrated stable trapping of targets ranging from 2. This large chamber also minimises acoustic streaming at the target trapping site. Two holes were made in the side of the chamber, for the transducers, with O-rings around the transducers added to provide a water-tight seal.
A function generator LXI, Keithley generated the alternating voltage used to drive the transducers at the resonant frequency of the system. A customized RF current amplifier is employed to ensure sufficient power for the transducers.
Ripe B. Gametes were individually harvested from multiple ascidian adults; eggs were mixed with sperm for fertilization. The embryos were then transferred to the acoustic-trapping sample chamber for imaging. The zebrafish Danio rerio transgenic line mbp:GFP 49 , which has cmlc2:GFP reporter expression in the heart was used to image heartbeat.
Adult zebrafish, up to 2 years of age, were used for breeding purposes. All experimental analyses in the manuscript were carried out on animals up to 5 days post-fertilisation. The relevant breeding and maintenance protocols were approved by the University of Edinburgh Institutional Animal Care and Use Committee. Zebrafish larva was transferred into the imaging chamber with a plastic pipette and acoustically trapped in the centre of the chamber. For drug treatment, a peristaltic pump minipulse 3, Gilson was used to circulate fluid between the sample chamber and a beaker though polyvinyl chloride PVC tubing.
For stage one, E3 medium with baseline tricaine was circulated between the sample chamber and the beaker in a closed loop. Starting at stage two, a high concentration of drug was added into the beaker, whilst the fluid was circulated in a closed loop, resulting in desired final concentration. For stage three, fresh medium with baseline tricaine was pumped into the sample chamber whilst the outlet was discharged to waste, so that the concentration of the drug decreased gradually.
The peristaltic pump was stopped while image stacks were taken, to minimise the disturbance caused. Fish were randomly allocated to each group from the same population. Blinding was not relevant to this study as all imaging and image analysis was automated. Optical flow was performed using the Horn—Schunck HS method 35 , which estimates the image displacements by minimising an objective function comprising the local spatial and temporal image gradients such as seen from LSFM image edges and features.
It is further regularised to a global smoothness, i. The HS method is particularly suited to mechanical deformation problems, as a continuity in the displacement field gradients is likely. The major advantage of the optical flow method over the image correlation techniques, which are commonly used in tracking mechanical deformation, is its computational speed. This speed enabled high-throughput analysis. The deformation of the heart, i. Thus, the total volumetric strain was calculated by integrating across frames. For each image sequence, the heartbeat rate and the volumetric strain amplitude were extracted for regions in the atrium and ventricle using Fourier analysis.
The power spectral density PSD was calculated for temporal measurements in each location. The frequency peak of the PSD is the beat rate, whilst the amplitude of the PSD at the peak, and its harmonics, were related to the amplitude of contraction Such analysis discards the contributions of other noise sources not related to the beat. Treuren, W. Live imaging of Aiptasia larvae, a model system for studying coral bleaching, using a simple microfluidic device.
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