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Solid state compounds exhibiting multiple and coupled macroscopic orders, named multiferroics, represent a challenge for both theoretical and experimental modern condensed-matter physics. Spins and the electric polarisation in conventional magnetic and ferroelectric materials can be manipulated on their fundamental timescales, by means of femtosecond laser pulses. In view of the resounding success and popularity of the all-optical approach, it is only natural to wonder about the application of this scheme to study the intrinsic coupling between spins and charges in multiferroics. Deeply fundamental questions arise: can ultrashort laser pulses deterministically activate, enhance or suppress the magnetoelectric coupling on the femtosecond timescale? Can these processes be triggered in a fully coherent fashion, thus being unrestrained by any thermal load? Which mechanism of spin-charge coupling is most favourable to overcome these overarching and daunting challenges? This problem is interdisciplinary in nature, requiring contributions from materials science and condensed matter physics from both theoretical and experimental perspectives. High-quality materials suitable for optical investigations have to be identified, synthetized and characterised. General and valid models offer then a guide to the plethora of possible light-induced processes, resulting in the desired ultrafast multiferroic manipulations. Finally, healthy experimental schemes, able to unambiguously track the ultrafast dynamics of either the ferroelectric or the magnetic order parameter have to be developed and implemented. Our motivation to write this review is to lay a broad and multidisciplinary foundation, which may be employed as a starting point for non-equilibrium approaches to the manipulation of the multiferroicity on the femtosecond timescale. This was also one of the main goals of the COST Action MAGNETOFON, whose network constitutes the core of the authors of this review. The present work thus represents a part of the scientific legacy of MAGNETOFON itself.

Electromagnetic radiation in the mid- to far-infrared spectral range represents an indispensable tool for the study of numerous types of collective excitations in solids and molecules. Short and intense pulses in this THz spectral range are, however, difficult to obtain. While wide wavelength-tunability is easily provided by free-electron lasers, the energies of individual pulses are relatively moderate, on the order of microjoules. Here we demonstrate a setup that uses cavity-dumping of a free-electron laser to provide single, picosecond-long pulses in the mid- to far-infrared frequency range. The duration of the Fourier-limited pulses can be varied by cavity detuning, and their energy was shown to exceed 100 {\mu}J. Using the aforementioned infrared pulse as a pump, we have realized a two-color pump-probe setup facilitating single-shot time-resolved imaging of magnetization dynamics. We demonstrate the capabilities of the setup first on thermally-induced demagnetization and magnetic switching of a GdFeCo thin film and second by showing a single-shot time-resolved detection of resonant phononic switching of the magnetization in a magnetic garnet., Comment: The following article has been submitted to/accepted by the Review of Scientific Instruments. After it is published, it will be found at http://rsi.aip.org/

Item does not contain fulltext IRMMW-THz 2022

Amorphous TbxCo100-x magnetic alloys exhibit a list of intriguing properties, such as perpendicular magnetic anisotropy, high magneto-optical activity, and magnetization switching using ultrashort ...

We resolve a significant controversy about how to understand and engineer single-shot all-optical switching of magnetization in ferrimagnets using femto- or picosecond-long heat pulses. By realistically modelling a generic ferrimagnet as two coupled macrospins, we comprehensively show that the net magnetization can be reversed via different pathways, using a heat pulse with duration spanning all relevant timescales within the non-adiabatic limit. This conceptual understanding is fully validated by experiments studying the material and optical limits at which the switching process in GdFeCo alloys loses its reliability. Our interpretation and results constitute a blueprint for understanding how deterministic all-optical switching can be achieved in alternative ferrimagnets using short thermal pulses.

Identifying an efficient pathway to change the order parameter via a subtle excitation of the coupled high-frequency mode is the ultimate goal of the field of ultrafast phase transitions. This is an especially interesting research direction in magnetism, where the coupling between spin and lattice excitations is required for magnetization reversal. Despite several attempts however, the switching between magnetic states via resonant pumping of phonon modes has not yet been demonstrated. Here we show how an ultrafast resonant excitation of the longitudinal optical phonon modes in magnetic garnet films switches magnetization into a peculiar quadrupolar magnetic domain pattern, unambiguously revealing the magneto-elastic mechanism of the switching. In contrast, the excitation of strongly absorbing transverse phonon modes results in thermal demagnetization effect only., Comment: 16 pages, 12 figures

Using the technique of double high-speed photography, we find that a femtosecond laser pulse is able to change the velocity of a moving domain wall in an yttrium iron garnet. The change depends on the light intensity and the domain wall velocity itself. To explain the results we propose a model in which the domain wall velocity is controlled by photo-induced generation of vertical Bloch lines.

The authors experimentally resolve the pulse- and temperature-dependent limits of single-shot alloptical magnetic switching in the compensated three dimensional ferrimagnet, revealing that the process is driven by exchange relaxation.

Thin-film patterned magnetic nanostructures are widely employed within perceived magnonic device architectures to guide and/or manipulate spin waves for data processing and communication purposes. Here, using micromagnetic simulations, we explore how the internal magnetic field nonuniformity inherent to patterned magnetic nanostructures can also be exploited to create spin-wave sources. The spin-wave emission is achieved through the resonant excitation of finite-sized regions of increased effective magnetic field formed near the edges of patterned structures. The phenomenon is rather universal and could be used to generate magnetodipole, dipole-exchange, and exchange dominated spin waves. Depending on the frequency of excitation and parameters of the nanostructures, the emitted spin waves may form either highly directional spin-wave caustic beams or more regular plane spin waves.

A heat-assisted route for subnanosecond magnetic recording is discovered for the dielectric bismuth-substituted yttrium iron garnet, known for possessing small magnetic damping. The experiments and simulations reveal that the route involves nonlinear magnetization precession, triggered by a transient thermal modification of the growth-induced crystalline anisotropy in the presence of a fixed perpendicular magnetic field. The pathway is rendered robust by the damping becoming anomalously large during the switching process. Subnanosecond deterministic magnetization reversal was achieved within just one-half of a precessional period, and this mechanism should be possible to implement in any material with suitably engineered dissimilar thermal derivatives of magnetization and anisotropy.

This work reports the development of perpendicular magnetic tunnel junctions, based on a multilayered stack of [Tb/Co] nanolayers, in which the magnetization can be reliably toggled using a single optical pulse. The helicity-independent single-shot switching of the magnetization in the Tb/Co multilayered stack was achieved using either 60 fs-long or 5 ps laser pulses with incident fluences down to 4.7 mJ/cm2. The magnetic switching was achieved for a Co-rich composition window of the multilayer corresponding to layer thickness ratios tCo/tTb between 1.3-1.5. This was confirmed for the multilayer alone as well as for the multilayer coupled to aCoFeB electrode, with a structure consisting of CoFeB/Ta/[Tb/Co]N. The optical switching is preserved even after annealing at 250°C in magnetic tunnel junctions (MTJ) electrodes, exhibiting a tunnel magnetoresistance (TMR) of 41% and RxA value of 150 Ωμm after its integration, measured on unpatterned MTJ stacks. These results represent the first step towards the development of hybrid spintronic photonic systems with fJ switching energies.

The one-dimensional planar magnonic crystals are usually fabricated as a sequence of stripes intentionally or accidentally separated by non-magnetic spacers. The influence of spacers on shaping the spin wave spectra is complex and still not completely clarified. We performed the detailed numerical studies of the one-dimensional single- and bi-component magnonic crystals comprised of a periodic array of thin ferromagnetic stripes separated by non-magnetic spacers. We showed that the dynamic dipolar interactions between the stripes mediated by non-magnetic spacer, even ultra-narrow, significantly shift up the frequency of the ferromagnetic resonance and simultaneously reduce the spin wave group velocity, which is manifested by the flattening of the magnonic band. We attributed these changes in the spectra to the modifications of dipolar pinning and shape anisotropy both dependent on the width of the spacers and the thickness of the stripes, as well as to the dynamical magnetic volume charges formed due to inhomogeneous spin wave amplitude.

The explosive growth of data and its related energy consumption is pushing the need to develop energy-efficient brain-inspired schemes and materials for data processing and storage. Here, we demonstrate experimentally that Co/Pt films can be used as artificial synapses by manipulating their magnetization state using circularly-polarized ultrashort optical pulses at room temperature. We also show an efficient implementation of supervised perceptron learning on an opto-magnetic neural network, built from such magnetic synapses. Importantly, we demonstrate that the optimization of synaptic weights can be achieved using a global feedback mechanism, such that the learning does not rely on external storage or additional optimization schemes. These results suggest there is high potential for realizing artificial neural networks using optically-controlled magnetization in technologically relevant materials, that can learn not only fast but also energy-efficient., Comment: 9 pages, 4 figures

The mechanism used to alter the features of propagating spin waves is a key component underpinning the functionality of high-frequency magnonic devices. Here, using experiment and micromagnetic simulations, we demonstrate the feasibility of a magnonic multiplexer in which the spin-wave beam is toggled between device output branches by the polarity of a small global bias magnetic field. Due to the anisotropy inherent in the dispersion of magnetostatic spin waves, the phase fronts of the output spin waves are asymmetrically tilted relative to the direction of the beam propagation (group velocity). We show how the phase tilts could be (partly) rectified in the magnonic waveguides of variable widths.

The wave solutions of the Landau–Lifshitz equation (spin waves) are characterized by some of the most complex and peculiar dispersion relations among all waves. For example, the spin-wave (“magnonic”) dispersion can range from the parabolic law (typical for a quantum-mechanical electron) at short wavelengths to the nonanalytical linear type (typical for light and acoustic phonons) at long wavelengths. Moreover, the long-wavelength magnonic dispersion has a gap and is inherently anisotropic, being naturally negative for a range of relative orientations between the effective field and the spin-wave wave vector. Nonuniformities in the effective field and magnetization configurations enable the guiding and steering of spin waves in a deliberate manner and therefore represent landscapes of graded refractive index (graded magnonic index). By analogy to the fields of graded-index photonics and transformation optics, the studies of spin waves in graded magnonic landscapes can be united under the umbrella of the graded-index magnonics theme and are reviewed here with focus on the challenges and opportunities ahead of this exciting research direction.

We demonstrate an approach to parallel all-optical writing of magnetic domains using spatial and temporal interference of two ultrashort light pulses. We explore how the fluence and grating periodicity of the optical transient grating influence the size and uniformity of the written bits. Using a total incident optical energy of 3.5 μJ, we demonstrate the capability of simultaneously writing 102 spatially separated bits, each featuring a relevant lateral width of ∼1 μm. We discuss viable routes to extend this technique to write individually addressable, sub-diffraction-limited magnetic domains in a wide range of materials.We demonstrate an approach to parallel all-optical writing of magnetic domains using spatial and temporal interference of two ultrashort light pulses. We explore how the fluence and grating periodicity of the optical transient grating influence the size and uniformity of the written bits. Using a total incident optical energy of 3.5 μJ, we demonstrate the capability of simultaneously writing 102 spatially separated bits, each featuring a relevant lateral width of ∼1 μm. We discuss viable routes to extend this technique to write individually addressable, sub-diffraction-limited magnetic domains in a wide range of materials.

Using a combination of experiment and simulation, the authors have investigated comprehensively how the spin-wave transmission across a curved magnonic waveguide is modified through rotation of an externally delivered uniform magnetic field. They reveal that, while the spin-wave transmission is reasonable when the bend is magnetized along an axis of symmetry, the transmission can be substantially improved (by a factor of 2) through just rotating the magnetic field by 15\ifmmode^\circ\else\textdegree\fi{} in a particular direction. To explain their results, the authors study the landscape of the internal magnetic field spanning the structure, and discuss how it can be tuned in order to optimally distribute the flow of anisotropic spin waves across networks of magnonic waveguides.

We report the development of a hybrid numerical / analytical model capable of mapping the spatially-varying distributions of the local ferromagnetic resonance (FMR) frequency and dynamic magnetic susceptibility in a wide class of patterned and compositionally modulated magnetic structures. Starting from the numerically simulated static micromagnetic state, the magnetization is deliberately deflected orthogonally to its equilibrium orientation, and the magnetic fields generated in response to this deflection are evaluated using micromagnetic software. This allows us to calculate the elements of the effective demagnetizing tensor, which are then used within a linear analytical formalism to map the local FMR frequency and dynamic magnetic susceptibility. To illustrate the typical results that one can obtain using this model, we analyze three micromagnetic systems boasting non-uniformity in either one or two dimensions, and successfully explain the spin-wave emission observed in each case, demonstrating the ubiquitous nature of the Schl\"omann excitation mechanism underpinning the observations. Finally, the developed model of local FMR frequency could be used to explain how spin waves could be confined and steered using magnetic non-uniformities of various origins, rendering it a powerful tool for the mapping of the graded magnonic index in magnonics.

This research has received funding from the European Union's Horizon 2020 research and innovation program under Marie Sklodowska-Curie Grant Agreement No. 644348 (MagIC) and from Ukrainian State Fund for Fundamental Research under project No. F71/73-2016 ('Multifunctional Photonic Structures').

Background Automated external defibrillators (AEDs) operated by lay persons are used in the UK in a National Defibrillator Programme promoting public access defibrillation (PAD). Methods Two strategies are used: (1) Static AEDs installed permanently in busy public places operated by those working nearby. (2) Mobile AEDs operated by community first responders (CFRs) who travel to the casualty. Results One thousand five hundred and thirty resuscitation attempts. With static AEDs, return of spontaneous circulation (ROSC) was achieved in 170/437 (39%) patients, hospital discharge in 113/437 (26%). With mobile AEDs, ROSC was achieved in 110/1093 (10%), hospital discharge in 32 (2.9%) (P < 0.001 for both variables). More shocks were administered with static AEDS 347/437 (79%) than mobile AEDs 388/1093 (35.5%) P < 0.001. Highly significant advantages existed for witnessed arrests, administration of shocks, bystander CPR before arrival of AED and short delays to start CPR and attach AED. These factors were more common with static AEDs. For CFRs, patients at home did less well than those at other locations for ROSC (P < 0.001) and survival (P = .006). Patients at home were older, more arrests were unwitnessed, fewer shocks were given, delays to start CPR and attach electrodes were longer. Conclusions PAD is a highly effective strategy for patients with sudden cardiac arrest due to ventricular fibrillation who arrest in public places where AEDs are installed. Community responders who travel with an AED are less effective, but offer some prospect of resuscitation for many patients who would otherwise receive no treatment. Both strategies merit continuing development.

Magnonics explores precessional excitations of ordered spins in magnetic materials---so-called spin waves---and their use as information and signal carriers within networks of magnonic waveguides. Here, we demonstrate that the nonuniformity of the internal magnetic field and magnetization inherent to magnetic structures creates a medium of graded refractive index for propagating magnetostatic waves and can be used to steer their propagation. The character of the nonuniformity can be tuned and potentially programmed using the applied magnetic field, which opens exciting prospects for the field of graded-index magnonics.

We have used time-resolved scanning Kerr microscopy (TRSKM) and micromagnetic simulations to demonstrate that, when driven by spatially uniform microwave field, the edges of patterned magnetic samples represent both efficient and highly tunable sources of propagating spin waves. The excitation is due to the local enhancement of the resonance frequency induced by the non-uniform dynamic demagnetizing field generated by precessing magnetization aligned with the edges. Our findings represent a crucial step forward in the design of nanoscale spin-wave sources for magnonic architectures, and are also highly relevant to the understanding and interpretation of magnetization dynamics driven by spatially-uniform magnetic fields in patterned magnetic samples.

Arabidopsis thaliana mutants originally isolated as hypersensitive to irradiation were screened for the ability to be transformed by Agrobacterium transferred DNA (T-DNA). One of four UV-hypersensitive mutants and one of two gamma-hypersensitive mutants tested showed a significant reduction in the frequency of stable transformants compared with radioresistant controls. In a transient assay for T-DNA transfer independent of genomic integration, both mutant lines took up and expressed T-DNA as efficiently as parental lines. These lines are therefore deficient specifically in stable T-DNA integration and thus provide direct evidence for the role of a plant function in that process. As radiation hypersensitivity suggests a deficiency in repair of DNA damage, that plant function may be one that is also involved in DNA repair, possibly, from other evidence, in repair of double-strand DNA breaks.

We have used Brillouin Light Scattering and micromagnetic simulations to demonstrate a point-like source of spin waves created by the inherently nonuniform internal magnetic field in the vicinity of an isolated antidot formed in a continuous film of yttrium-iron-garnet. The field nonuniformity ensures that only well-defined regions near the antidot respond in resonance to a continuous excitation of the entire sample with a harmonic microwave field. The resonantly excited parts of the sample then served as reconfigurable sources of spin waves propagating (across the considered sample) in the form of caustic beams. Our findings are relevant to further development of magnonic circuits, in which point-like spin wave stimuli could be required, and as a building block for interpretation of spin wave behavior in magnonic crystals formed by antidot arrays.

We demonstrate a magnonic beam splitter that works by inter-converting magnetostatic surface and backward-volume spin waves propagating in orthogonal sections of a T-shaped yttrium iron garnet structure. The inter-conversion is enabled by the overlap of the surface and volume spin wave bands. This overlap results from the demagnetising field induced along the transversely magnetised section(-s) of the structure and the quantization of the transverse wave number of the propagating spin waves (which are therefore better described as waveguide modes). In agreement with numerical micromagnetic simulations, our Brillouin light scattering imaging experiments reveal that, depending on the frequency, the incident fundamental waveguide magnonic modes may also be converted into higher order waveguide modes. The magnonic beam splitter demonstrated here is an important step towards the development of parallel logic circuitry of magnonics.

Objective: To report on the effectiveness of an initiative to reduce deaths from sudden cardiac arrest occurring in busy public places. Setting: 110 such places identified from ambulance service data as high risk sites. Patients: 172 members of the public who developed cardiac arrest at these sites between April 2000 and March 2004. 20 592 defibrillator months’ use is reported, representing one automated external defibrillator (AED) use every 120 months. Intervention: 681 AEDs were installed; staff present at the sites were trained in basic life support and to use AEDs. Main outcome measures: Initial rhythm detected by AED, restoration of spontaneous circulation, survival to hospital discharge. Results: 172 cases of cardiac arrest were treated by trained lay staff working at the site before the arrival of the emergency services during the period. A shockable rhythm was detected in 135 (78%), shocks being administered in 134 an estimated 3–5 minutes after collapse; 38 (28.3%) patients subsequently survived to hospital discharge. Spontaneous circulation was restored in five additional patients who received shocks but died later in hospital. In 37 cases no shock was initially indicated; one patient survived after subsequent treatment by paramedics, cardiopulmonary resuscitation having been given soon after collapse. Overall, irrespective of the initial rhythm, 39 patients (22.7%), were discharged alive from hospital. For witnessed arrests of presumed cardiac cause in ventricular fibrillation (an international Utstein comparator) survival was 37 of 124 (29.8%). Conclusions: The use of AEDs by lay people at sites where cardiac arrest commonly occurs is an effective strategy to reduce deaths at these sites.

If research against malaria is to have a major impact on health, then all available resources and expertise must be harnessed for maximal effect. Bringing together scientists, funding organisations and disease control experts, the Multilateral Initiative on Malaria (MIM) has made significant progress since its creation in 1997 in promoting and co-ordinating scientific research against malaria. Enhancing global collaboration, mobilizing resources, promoting capacity building in Africa and strengthening links between research and control are major emphases of MIM. The initiative primarily acts through drawing together diverse international research activities, setting well considered priorities, and promoting effective targeting of energies and funds. This article is a personal view on MIM contributed by the Wellcome Trust as the nominated co-ordinator during 1998 and part of 1999. It aims to set out the rationale for MIM, to explain the principles of its operation and to illustrate achievement during its first phase.

Ferromagnetic resonance in thin films and heterostructures is studied by micromagnetic simulation. Using a Fourier transform, we obtain the power spectrum of modes of precession and demonstrate that they agree with experimental results. Additional resonance modes associated with demagnetization effects are observed and studied as a function of the sample dimensions. Sufficiently confined geometries lead to a reorientation of the resonance mode, and a dramatic change in its frequency. Finally, the simulations are extended to exchange-coupled bilayers where energy is transferred between magnetic materials. © 2014 AIP Publishing LLC.

The Multilateral Initiative on Malaria (MIM) is an international alliance of organisations and individuals. It aims to maximise the impact of scientific research against malaria, through strengthening research capacity in Africa, promoting global collaboration and co-ordination, and increasing available resources. Since its establishment in 1997, the initiative has generated a remarkable level of enthusiasm and activity. Many new scientific partnerships have been established, enabled by enhanced communications and novel funding mechanisms. Dovetailing of research activities with control programmes is also improving. The challenges posed by malaria remain great, however, and in order to achieve a sustainable impact it will be crucial for the research community to capitalise on what has been achieved to date and to maintain the momentum for action well into the next millennium. This article is a personal view contributed by the Wellcome Trust as the nominated co-ordinator for MIM during 1998 and a leading international funder of malaria research. It aims to explain how the novel malaria initiative operates, to summarise some of its key outcomes, and to set out the perspectives for the future.

This article describes an action research project designed to develop a teaching programme which would enable students to bridge the theory-practice gap they experienced while on placement in a gynaecology unit.

Lipoxygenase-mediated oxidation of fatty acids has long been implicated in the production of off-flavors in soybean products. This assumption was tested by use of preparations from soybean lines nearly isogenic to the cultivar Century that lack the lipoxygenase isozyme or isozyme combinations L1, L2, L3, L1 + L3, or L2 + L3. Near-isogenic lines were used to ensure that any effects observed were due to elimination of lipoxygenase isozymes, and not to other unrecognized genetic differences between lines. Full-fat soy flour and unblanched soymilk preparations from the lines were evaluated by a six-member taste panel for eight flavor and/or aroma attributes common to soybeans. By comparison to near-isogenic controls, removal of the L2 isozyme from soymilk preparations produced significantly lower scores for beany, rancid and oily flavor and aroma attributes, as well as higher scores for dairy and cereal flavor and aroma attributes. Similar trends were noted for soy flour flavor attributes. Thiobarbituric acid (TBA) numbers, a measure of lipid oxidation, were lower in homogenized soy flour suspensions from lines lacking L2. Removal of the L1 and L3 isozymes did not result in improved flavor scores or lower TBA numbers. Total oil content and the fatty acid profile of the near isolines did not vary appreciably. The results indicated that genetic removal of the L2 isozyme may reduce off-flavors in soy products.

A cultivar lacking the glycinin subunit A5A4B3 ('Raiden') was crossed with one lacking the α'-subunit of β-conglycinin ('Keburi'). Analysis of F2 and F3 progeny indicated that the missing bands of the A5A4B3 and the α'-subunit were each controlled by a recessive allele of two independently segregating genes. Gene symbols Gy 4/gy 4 and Cgy 1/cgy 1 were proposed for the genes which confer the presence or absence of the glycinin and conglycinin subunits, respectively.

This study describes a major gene which controls lipoxygenase-3 (L-3) activity in soybean [Glycine max (L.) Merr.]. Cultlvars ‘Wasenatsu’ (PI 417 458) and ‘Ichigowase’ (PI 205 085) were found to L-3 by both immunological and electrophoretic methods. The inheritance of this trait was determined from progeny of crosses between Wasenatsu and either ‘Century’ or ‘Raiden’, two cultlvars that contain high levels of L-3. Segregation ratios in F₂ and F₃ seeds from selfed plants indicated that absence of L-3 was due to a single allele that was recessive to the one controlling the presence of the enzyme. Comparable results have been obtained using progeny from the cross Ichigowase ✕ PI 408 251. The latter parent contains L-3 but lacks L-1. We propose that the dominant allele be called Lx₃, whereas the recessive one be designated lx₃.

The influence of the novel hydroxynaphthoquinone 566C80 on exoerythrocytic development of Plasmodium berghei was examined in Brown Norway rats. The procedure employed was designed to identify residual activity of the drug against tissue merozoites emerging into the bloodstream and to distinguish this from any observed causal prophylactic activity against the liver stages. Single oral doses of 10 and 1 mg/kg of 566C80 administered 3 hours after sporozoite-inoculation were effective in preventing the appearance of a patent parasitaemia, while a dose of 0.1 mg/kg significantly reduced the severity of the ensuing blood infection. There was a pronounced residual effect of 566C80 against the blood forms at a dose of 10 mg/kg, a slight residual effect at a dose of 1 mg/kg, but no apparent residual effect at 0.1 mg/kg. At the time when EE merozoites would normally emerge into the bloodstream, an aliquot of blood was sub-inoculated into mice from sporozoite-infected, 566C80-treated rats. This procedure confirmed that 566C80 is active against the exoerythrocytic stages of Plasmodium berghei.

Three genes which code for variant β-conglycinin subunits were identified. Alleles Cgy 1 (S) and Cgy 2 (S) were codominant with Cgy 1 and Cgy 2 and produced α' and α subunits, respectively, with reduced electrophoretic mobility. Allele Cgy 3 (D) increased the mobility of at least one polypeptide in the β subunit family and exhibited incomplete dominance. Gene loci Cgy 2/Cgy 2 (S) and Cgy 3 (D) /cgy 3 (D) were linked, whereas Cgy 1/Cgy 1 (S) / cgy 1 segregated independently of the others. Techniques developed for purification of normal β-conglycinin subunits were effective in purifying the altered subunits. Deglycosylated variant proteins from seeds containing the alleles Cgy 1 (S) , Cgy 2 (S) , or Cgy 3 (D) also has altered mobility relative to deglycosylated normal proteins. Therefore, the altered subunits contained changes in their amino acid sequences rather than in their carbohydrate moieties. This interpretation is consistent with the observed codominant or incompletely dominant mode of inheritance for these alleles and suggests that each contains an altered nucleotide sequence in the structural gene. A fourth variant, which exhibited doublet α' and a electrophoretic bands, was inherited in a recessive fashion. Deglycosylated subunit proteins from this variant were identical in electrophoretic mobility to those of the deglycosylated normal protein. This suggests that the doublet phenotype resulted from an alteration in the carbohydrate moiety of these subunits. The gene or genes which condition this variant presumably are required for normal post-translational modification of the subunit carbohydrates and as such may be useful for investigating these events.

The in vitro exoerythrocytic (EE) of Plasmodium berghei was compared in primary rat and mouse hepatocytes and the human hepatoma cell line HepG2. All of the cell-types supported the full maturation of EE stages, but the HepG2 cells were much more susceptible to infection than the primary rodent hepatocytes and were also the most efficient host cells. Following refinement of culture techniques, the development of EE forms which is now observed in HepG2 cells closely reflects that occurring in vivo with respect to the morphology and size of parasites and their rate of maturation. Furthermore, high densities of parasites are reproducibly achieved. A detailed description is presented of exoerythrocytic development in HepG2 cells. The application of these cultures to chemosensitivity studies is discussed and the relative advantages of employing cell lines or primary hepatocytes as host cells in such a system are considered.