Circular Field Research Articles

Investigation of the effects of the step size of Geant4 electromagnetic physics on the depth dose simulation of a small field proton beam

Dose distribution, especially the Bragg peaks or percentage depth doses (PDDs) in a small proton field, are strongly influenced by the field size. Simulation is problematic because of the lack of lateral proton equilibrium. The aim of this study is to investigate the influence of the step size of Geant4 on the simulation of the depth dose, and to suggest the best combination of parameters for small-field proton simulation. In this work, the emstandard_opt3, emstandard_opt4 and emlivermore models (with or without lateral displacement models and guard volume) were examined for the wobbling proton beams in a water phantom. The PTSim based on Geant4 was used to simulate the transport and interaction of protons. These simulations were first benchmarked by large-field measurements and then implemented in various small-field simulations in order to investigate the effects of various physical parameters on the depth dose distribution under conditions of non-equilibrium protons. The comparison between measurement and simulation data was carried out on small fields, such as a circular field with a diameter of 10 mm and a square field of 30 × 30 mm2 for three different proton beam energies. The results showed that, at most, the dose deviation between G4EmStandardPhysics models and measurement was up to 9.7%, 11.1% and 14.48% in the plateau area located at about half the beam range for 110, 150 and 190 MeV, respectively. Small-field proton simulations showed that Geant4 v10.04.p02, emstandard_opt3 multiple Coulomb scattering models and with-Guard Volume offer the identical PDD compared to measurements.

The current magnetization hypothesis as a microscopic theory of the Ørsted magnetic field induction

A wire that conducts an electric current will give rise to a circular magnetic field (the Ørsted magnetic field), which can be calculated using the Maxwell–Ampere equation. For wires with diameters in the macroscopic scale, the Maxwell–Ampere equation is an established physical law that can reproduce a range of experimental observations. A key implication of this equation is that the induction of Ørsted magnetic field is a result of the displacement of charge. A possible microscopic origin of Ørsted magnetic induction was suggested in [J. Mag. Mag. Mat. 504, 166660 (2020)] (will be called the current magnetization hypothesis (CMH) thereupon). The present work establishes computationally, using simplified wire models, that the CMH reproduces the results of the Maxwell–Ampere equation for wires with a square cross section. I demonstrate that CMH can resolve the apparent contradiction between the observed magnetic field and that predicted by the Maxwell–Ampere equation in nanowires, as was reported in [Phys. Rev. B 99, 014436 (2019)]. The CMH shows that a possible reason for such contradiction is the presence of non-conductive surface layers in electric conductors.

Motion synchronicity of a micro-magnetic-particle chain in a rotating field

A magnetic chain consisted of micro-sized beads in a rotating magnetic field is experimented to observe its motion synchronicity with the external field. If the field frequency is sufficiently high, reverse motion occurs to slow down the average angular speed, so that the chain rotates much slower than the external field. A square field configuration, in which the instantaneous strength and angular speed vary with time within every rotating period, is proposed to improve the chaining stability and the motion synchronicity while a same overall frequency with the conventionally used circular field configuration is preserved.

Dose calculations for preclinical radiobiology experiments conducted with single-field cabinet irradiators.

To provide percentage depth dose (PDD) data along the central axis for dosimetry calculations in small-animal radiation biology experiments performed in cabinet irradiators. The PDDs are provided as a function of source-to-surface distance (SSD), field size, and animal size. The X-ray tube designs for four biological cabinet irradiators, the RS2000, RT250, MultiRad350, and XRAD320, were simulated using the BEAMnrc Monte Carlo code to generate 160, 200, 250, and 320kVp photon beams, respectively. The 320kVp beam was simulated with two filtrations: a soft F1 aluminium filter and a hard F2 thoraeus filter made of aluminium, tin, and copper. Beams were collimated into circular fields with diameters of 0.5-10cm at SSDs of 10-60cm. Monte Carlo dose calculations in 1-5-cm diameter homogeneous (soft tissue) small-animal phantoms as well as in heterogeneous phantoms with 3-mm diameter cylindrical lung and bone inserts (rib and cortical bone) were performed using DOSXYZnrc. The calculated depth doses in three test-cases were estimated by applying SSD, field size, and animal size correction factors to a reference case (40-cm SSD, 1-cm field, and 5-cm animal size), and these results were compared with the specifically simulated (i.e., expected) doses to assess the accuracy of this method. Dosimetry for two test-case scenarios of 160 and 250 kVp beams (representative of end-user beam qualities) was also performed, whereby the simulated PDDs at two different depths were compared with the results based on the interpolation from reference data. The depth doses for three test-cases calculated at 200, 320kVp F1, and 320kVp F2 with half value layers (HVLs) ranging from ∼0.6to 3.6mm Cu, agreed well with the expected doses, yielding dose differences of 1.2%, 0.1%, and 1.0%, respectively. The two end-user test-cases for 160 and 250 kVp beams with respective HVLs of ∼0.8 and 1.8mm Cu yielded dose differences of 1.4% and 3.2% between the simulated and the interpolated PDDs. The dose increase at the bone-tissue proximal interface ranged from 1.2 to 2.5 times the dose in soft tissue for rib and 1.3 to 3.7 times for cortical bone. The dose drop-off at 1-cm depth beyond the bone ranged from 1.3% to 6.0% for rib and 3.2% to 11.7% for cortical bone. No drastic dose perturbations occurred in the presence of lung, with lung-tissue interface dose of>99% of soft tissue dose and<3% dose increase at 1-cm depth beyond lung. The developed dose estimation method can be used to translate the measured dose at a point to dose at any depth in small-animal phantoms, making it feasible for preclinical calculation of dose distributions in animals irradiated with cabinet-style irradiators. The dosimetric impact of bone must be accurately quantified as dramatic dose perturbations at and beyond the bone interfaces can occur due to the relative importance of the photoelectric effect at kilovoltage energies. These results will help improve dosimetric accuracy in preclinical experiments.

Probing the orbital angular momentum of intense vortex pulses with strong-field ionization

With the rapid development of femtosecond lasers, the generation and application of optical vortices have been extended to the regime of intense-light-matter interaction. The characterization of the orbital angular momentum (OAM) of intense vortex pulses is very critical. Here, we propose and demonstrate a novel photoelectron-based scheme that can in situ distinguish the OAM of the focused intense femtosecond optical vortices without the modification of light helical phase. We employ two-color co-rotating intense circular fields in the strong-field photoionization experiment, in which one color light field is a plane wave serving as the probing pulses and the other one is the vortex pulses whose OAM needs to be characterized. We show that by controlling the spatial profile of the probing pulses, the OAM of the vortex pulses can be clearly identified by measuring the corresponding photoelectron momentum distributions or angle-resolved yields. This work provides a novel in situ detection scenario for the light pulse vorticity and has implications for the studies of ultrafast and intense complex light fields with optical OAM.

Topological Model of the Pseudogap State: Experimental Signatures

We summarize the basic ideas of our topological model of the pseudogap state of high temperature superconductors (HTS) as a condensate of charged magnetic monopoles, with a focus on new experimental signatures. These include the surface quantum Hall effect, the generation of electric fields when applying magnetic fields by the oblique Meissner effect, and the generation of circular electric fields surrounding electric currents by the oblique Ampère law.

A Looming Spatial Localization Neural Network Inspired by MLG1 Neurons in the Crab Neohelice.

Similar to most visual animals, the crab Neohelice granulata relies predominantly on visual information to escape from predators, to track prey and for selecting mates. It, therefore, needs specialized neurons to process visual information and determine the spatial location of looming objects. In the crab Neohelice granulata, the Monostratified Lobula Giant type1 (MLG1) neurons have been found to manifest looming sensitivity with finely tuned capabilities of encoding spatial location information. MLG1s neuronal ensemble can not only perceive the location of a looming stimulus, but are also thought to be able to influence the direction of movement continuously, for example, escaping from a threatening, looming target in relation to its position. Such specific characteristics make the MLG1s unique compared to normal looming detection neurons in invertebrates which can not localize spatial looming. Modeling the MLG1s ensemble is not only critical for elucidating the mechanisms underlying the functionality of such neural circuits, but also important for developing new autonomous, efficient, directionally reactive collision avoidance systems for robots and vehicles. However, little computational modeling has been done for implementing looming spatial localization analogous to the specific functionality of MLG1s ensemble. To bridge this gap, we propose a model of MLG1s and their pre-synaptic visual neural network to detect the spatial location of looming objects. The model consists of 16 homogeneous sectors arranged in a circular field inspired by the natural arrangement of 16 MLG1s' receptive fields to encode and convey spatial information concerning looming objects with dynamic expanding edges in different locations of the visual field. Responses of the proposed model to systematic real-world visual stimuli match many of the biological characteristics of MLG1 neurons. The systematic experiments demonstrate that our proposed MLG1s model works effectively and robustly to perceive and localize looming information, which could be a promising candidate for intelligent machines interacting within dynamic environments free of collision. This study also sheds light upon a new type of neuromorphic visual sensor strategy that can extract looming objects with locational information in a quick and reliable manner.

Dosimetric Characterization of Small Radiotherapy Electron Beams Collimated by Circular Applicators with the New Microsilicon Detector

High-energy small electron beams, generated by linear accelerators, are used for radiotherapy of localized superficial tumours. The aim of the present study is to assess the dosimetric performance under small radiation therapy electron beams of the novel PTW microSilicon detector compared to other available dosimeters. Relative dose measurements of circular fields with 20, 30, 40, and 50 mm aperture diameters were performed for electron beams generated by an Elekta Synergy linac, with energy between 4 and 12 MeV. Percentage depth dose, transverse profiles, and output factors, normalized to the 10 × 10 cm2 reference field, were measured. All dosimetric data were collected in a PTW MP3 motorized water phantom, at SSD of 100 cm, by using the novel PTW microSilicon detector. The PTW diode E and the PTW microDiamond were also used in all beam apertures for benchmarking. Data for the biggest field size were also measured by the PTW Advanced Markus ionization chamber. Measurements performed by the microSilicon are in good agreement with the reference values for all the tubular applicators and beam energies within the stated uncertainties. This confirms the reliability of the microSilicon detector for relative dosimetry of small radiation therapy electron beams collimated by circular applicators.

Manastir Mileševa - analiza i uklapanje fragmenata fresaka i izrada kopija spojenih ulomaka

In the course of two successive projects, the first in 2005 and the second in 2020, work on the fragments of frescoes in Mileševa resulted in the integration of five ensembles that could be reconstructed into the basic outline. In addition to this, certain ensembles were integrated that we cannot present in the same way either because we lack the knowledge about the complete appearance or because it is impossible to accurately determine the edge of the scene. As for individual figures, very likely from the first zone, a face from the 13th century was partly integrated and the figure of a monk from the 16th century. Of the inscriptions, two were partly established, the first which probably indicated the name Stefan, from the 16th century, and the other inscription in the circular field beside the Mother of God, containing the phrase 'of God' (Serb. B(o)žia), from the 16th or the 17th century. A right hand was partly integrated from the ensemble of a colossal figure, belonging to which were two fragments of an eye. We believe that this was a bust of Christ that was at the top of the Eastern wall of the narthex. Originating perhaps from the same ensemble is an ensemble of five integrated fragments, as well as two more smaller integrated ensembles, which could represent the lower part of Christ's body, in the scene of the Crucifixion. The red mineral mercury (cinnabarite) was used in addition to the earth pigments in the artist's palette, as well as ultramarine, lapis lazuli. The use of 24-karat gold leaf was confirmed on the fragment of a nimbus. Since pure gold was used only on the nimbuses in the narthex, and not gilded silver, clearly, this fragment was from the narthex, as we had assumed.

Ultrafast high energy electron lens radiography suitable for transient electromagnetic field diagnosis

Transient electromagnetic fields — during or after laser/particle beam-target interaction — are a significant and hardly explored parameter. This paper proposes a new method for measuring transient electromagnetic fields, based on ultrafast high-energy electron lens radiography, that has a high tolerance for matter in the diagnosed region. With this method, a continuous point strength diagnosis helps to obtain delicate. Furthermore, dual-band diagnosis can be used to determine the field direction. To verify its feasibility, a 50 MeV electron lens radiography beamline was designed and optimized and a preliminary simulation for diagnosing circular magnetic fields ranging from 170 T·μm to 680 T·μm was performed. For a number density of 2000/pixel and ±10% non-uniformity, ±15% diagnostic field strength accuracy has been obtained. The direction diagnosis also works well. Combined with the advantages of high-energy electron beams, ultrafast high-energy electron lens radiography is suitable for transient electromagnetic field diagnosis.

Misalignment Insensitive Wireless Power Transfer System Using a Hybrid Transmitter for Autonomous Underwater Vehicles

Compared to air surroundings, the marine environment is not stable due to the influence of ocean currents and other factors. Misalignments always occur inevitably when autonomous underwater vehicles are charging wirelessly in the docking station. Therefore, misalignment insensitive underwater wireless power transfer system need to be investigated. In this article, a novel hybrid transmitter composed of conical and planar spiral coils is proposed that greatly improves the misalignment tolerance and transfer performance. First, the coil tilt angle theory (CTAT) is presented and verified to determine the optimum tilt angle of conical coil. Then, based on the CTAT, a circular uniform magnetic field zone with a diameter of 30 cm in charging plane can be achieved by flexibly designing the hybrid transmitter. Moreover, a three-dimensional finite-element simulation software is employed to study the eddy current loss under different circumstances. Finally, experimental results show that the proposed transmitter has better performance in output power and power transfer efficiency (PTE) stability within the possible working region compared with conventional transmitters. It has demonstrated that the output power changes only within 5.7&#x0025; and the PTEs maintain at approximately 86&#x0025; in excessive misalignment area with transfer distance of 2 cm.

Influence of Jaw Setting in the Determination of Stereotactic Small-Field Output Factors with Different Detectors.

Background:The experimental determination of relative output factors presents the greatest challenge, especially for small fields with different detectors. The aim of this study is to evaluate the influence of jaw positions on small-field output factors for the fields defined by micro-multileaf collimator and circular cones with different detectors.Materials and Methods:The stereotactic output factors were measured on Primus linear accelerator with BrainLab micro-multileaf collimator (mMLC) and circular cones as add-on tertiary collimators. Square field sizes ranging from 0.6 cm × 0.6 cm to 9.8 cm × 9.8 cm and circular fields of diameter ranging from 1.0 cm to 4.0 cm were defined by mMLC and circular cones, respectively. The influence of jaw position on output factor was assessed for different geometric configurations with three different detectors.Results:The values obtained with PinPoint ion chamber were consistent with microDiamond detector for fields greater than 24 mm × 24 mm, but an underestimation of 23.9% was noticed in 6 mm x 6 mm field size. For the mMLC defined field size of 6 mm × 6 mm, when the X-Y jaw was moved from 8 mm × 8 mm to 80 mm × 80 mm, an increase in the output by a factor of 1.7 was observed with both microDiamond and stereotactic radiosurgery diode, whereas an increase in output by a factor of 1.9 was noticed with PinPoint ion chamber.Conclusion:Output factors obtained with different detectors show high differences in the smallest field size for all collimating systems. This study confirms that the position of X and Y jaw above the tertiary collimator significantly influences the small-field output factor.

Design and validation of a synchrotron proton beam line for FLASH radiotherapy preclinical research experiments.

The main purpose of this work was to generate and validate the dosimetric accuracy of proton beams of dimensions that are appropriate for in vivo small animal and in vitro ultrahigh dose rate (FLASH) radiotherapy experiments using a synchrotron-based treatment delivery system. This study was performed to enable future investigations of the relevance of a spread-out Bragg peak (SOBP) under FLASH conditions. The spill characteristics of the small field fixed horizontal beam line were modified to deliver accelerated protons in times as short as 2ms and to control the dose delivered. A Gaussian-like transverse beam profile was transformed into a square uniform one at FLASH dose rates, while avoiding low-dose regions, a crucial requirement to protect normal tissue during FLASH irradiation. Novel beam-shaping devices were designed using Monte Carlo techniques to produce up to about 6cm3 of uniform dose in SOBPs while maximizing the dose rate. These included a scattering foil, a conical flattening filter to maximize the flux of protons into the region of interest, energy filters, range compensators, and collimators. The shapes, sizes, and positions of the components were varied to provide the required field sizes and SOBPs. The designed and fabricated devices were used to produce 10-, 15-, and 20-mm diameter, circular field sizes and 10-, 15-, and 20-mm SOBP modulation widths at uniform physical dose rates of up to 375Gy/s at the center of the SOBP and a minimum dose rate of about 255Gy/s at the entrance, respectively, in cylindrical volumes. The flatness of lateral dose profiles at the center could be adjusted to within ±1.5% at the center of the SOBP. Assessment of systematic uncertainties, such as impact of misalignments and positioning uncertainties, was performed using simulations, and the results were used to provide appropriate adjustments to ensure high-accuracy FLASH beam delivery for both in vitro and in vivo preclinical experiments. It is feasible to use synchrotron-generated proton beams of sufficient dimensions for FLASH radiobiology experiments. We expect to use the system we developed to acquire in vitro and in vivo small animal FLASH radiobiology data as a function of dose, dose rate, oxygen content, and linear energy transfer to help us understand the underlying mechanisms of the FLASH phenomenon.

Luminosity thresholds of colored surfaces are determined by their upper-limit luminances empirically internalized in the visual system.

We typically have a fairly good idea whether a given object is self-luminous or illuminated, but it is not fully understood how we make this judgment. This study aimed to identify determinants of the luminosity threshold, a luminance level at which a surface begins to appear self-luminous. We specifically tested a hypothesis that our visual system knows the maximum luminance level that a surface can reach under the physical constraint that a surface cannot reflect more light than any incident light and applies this prior to determine the luminosity thresholds. Observers were presented with a 2-degree circular test field surrounded by numerous overlapping colored circles and luminosity thresholds were measured as a function of (i) the chromaticity of the test field, (ii) the shape of surrounding color distribution, and (iii) the color of the illuminant of the surrounding colors. We found that the luminosity thresholds peaked around the chromaticity of test illuminants and decreased as the purity of the test chromaticity increased. However, the loci of luminosity thresholds across chromaticities were nearly invariant to the shape of the surrounding color distribution and generally resembled the loci drawn from theoretical upper-limit luminances and upper-limit luminance boundaries of real objects. These trends were particularly evident for illuminants on the black-body locus and did not hold well under atypical illuminants, such as magenta or green. These results support the idea that our visual system empirically internalizes the gamut of surface colors under natural illuminants and a given object appears self-luminous when its luminance exceeds this internalized upper-limit luminance.

The effect of direct current in a steel rod on the switching field dependence of magnetic permeability

It is theoretically shown that in cases where the process of irreversible magnetization reversal of ferromagnetic steels is determined by displacements of only 180° domain boundaries, the dependences of reversible permeability on the switching field in low-carbon steels when a direct current is passed along a rod sample should have two maxima instead of the usual one that occurs in the absence of this current. The distances between the maxima of these peaks linearly depend on the value of the constant component of the current and, consequently, on the constant circular magnetic field caused by it, perpendicular to the switching field. This phenomenon should occur both for undeformed steel samples in the state after annealing and for samples after plastic stretching. In the latter case, elastic tensile stresses of such magnitude should act to compensate for internal residual compressive stresses. The fields of both peaks of magnetic permeability in these two cases are close to each other.

Ultra Low Frequency Wave Produced by Underwater Oscillating Sphere and Its Measurement

When an underwater target moves in viscous fluid, it may cause the periodic movement of the surrounding fluid and generate ultra-low-frequency (ULF) gravity waves. The initial domain of the gravitational surface wave propagating above the moving target is named circular wave. This article studies the ULF circular wave generated by underwater oscillating sphere, which will provide basis for underwater long-range target detection. Firstly, the circular wave caused by the sphere oscillation in a finite deep fluid is studied based on the theory of linear potential flow. Meanwhile, the multipole expansion theory is established to solve the circular wave field. Secondly, the interface wave generated by the target oscillation in a two-layer fluid are numerically analyzed by comparison with the free surface fluctuation of a single-layer fluid. The results show that the amplitude of the internal interface displacement (AIID) is smaller than that of the free surface (AFSD). When the sphere is in the lower layer, the layering effect of the fluid has significant influences on the AFSD. Finally, the results of the pool experiment verified that the wave generated by the oscillating sphere is the surface gravity wave. Furthermore, the change trend of the test result is consistent with the simulation result.

Vector Fuzzy c-Spherical Shells (VFCSS) over Non-Crisp Numbers for Satellite Imaging

The conventional fuzzy c-spherical shells (FCSS) clustering model is extended to cluster shells involving non-crisp numbers, in this paper. This is achieved by a vectorized representation of distance, between two non-crisp numbers like the crisp numbers case. Using the proposed clustering method, named vector fuzzy c-spherical shells (VFCSS), all crisp and non-crisp numbers can be clustered by the FCSS algorithm in a unique structure. Therefore, we can implement FCSS clustering over various types of numbers in a unique structure with only a few alterations in the details used in implementing each case. The relations of VFCSS applied to crisp and non-crisp (containing symbolic-interval, LR-type, TFN-type and TAN-type fuzzy) numbers are presented in this paper. Finally, simulation results are reported for VFCSS applied to synthetic LR-type fuzzy numbers; where the application of the proposed method in real life and in geomorphology science is illustrated by extracting the radii of circular agricultural fields using remotely sensed images and the results show better performance and lower cost computational complexity of the proposed method in comparison to conventional FCSS.

Probing tunneling dynamics of dissociative H2 molecules using two-color bicircularly polarized fields

Probing and manipulating the electronic motion in the ultrafast laser molecular interaction provides the pathways for quantum imaging and controlling chemical reactions. Recently, the emerging application of attosecond metrology of ultrafast electron dynamics has accessed the time scale of the most fundamental processes in molecular chemical reactions. Here, we probe the tunneling dynamics of internuclear-dependent dissociative reaction of ${\mathrm{H}}_{2}$ with angular streaking using two-color bicircularly polarized femtosecond laser pulses. By measuring high-resolution photoelectron spectroscopy, we disentangle the orientation and internuclear-distance dependent effect of the long-range Coulomb potential and the initial phase on molecular-frame photoelectron momentum distributions, and stereo extract the phase gradient of the tunneling electron wave packets and Wigner time delay during the dissociative ionization using two-color bicircular fields. The work has an insight into the clocking of ultrafast spatiotemporal photoelectron dynamics and the quantum control of molecular chemical processes via sculptured circular fields, which can be applied to polyatomic molecules.

Validation of a Novel Cone-Less Set-up for Electron FLASH Radiation Delivery on a Clinical-Use Linear Accelerator

<h3>Purpose/Objective(s)</h3> Ultra-high dose rate (FLASH) radiotherapy (RT) at ≥40 Gray per second has been shown preclinically to achieve improved normal tissue sparing while maintaining tumor control similar to that of conventional dose-rate RT. Many published FLASH-RT delivery models are inaccessible for widespread use and/or not applicable for clinical translation. We previously described a model for reversible configuration of a clinical linear accelerator (LINAC) that can deliver ∼16-18 MeV electron FLASH-RT at source-to-surface distances (SSDs) < 95 cm. However, it precludes the use of a standard electron cone. This proof-of-concept study will characterize the beam profiles from a novel cone-less set-up, to verify its feasibility as a widely accessible method of electron FLASH-RT delivery for the intention of clinical treatment. <h3>Materials/Methods</h3> This novel set-up employs a flat 25 × 25 cm applicator with custom cut-outs that lies within the accessory mount at 66.6 cm SSD of a standard treatment delivery system. We tested a 10 × 10 cm circular field size at a target distance of 80 cm SSD (selected to maintain FLASH dose rates). Radiographic film and an IC Profiler were used to evaluate penumbra width, beam flatness, symmetry, and percentage depth dose (PDD). FLASH-RT was delivered in 20 pulses with 3 independent measurements each using film and the profiler. This was compared to a conventional 16 MeV beam using a standard cone with a 10 × 10 cm field size at 100 cm SSD. <h3>Results</h3> Our novel cone-less FLASH set-up achieved a beam profile that was similar to the conventional electron set-up. Respectively, for the cone-less and conventional set-up, measured at a standardized depth of half R85, penumbra width was 1.13 cm and 1.15 cm, and uniformity index was 0.72 and 0.74 (defined as the ratio of the areas inside the 90% and 50% isodose lines); measured at a standardized depth of R95, flatness (defined as the maximum dose deviation from the central axis at a specific depth over an area confined within lines 2 cm inside the geometric edge of fields) was 1.5% and 4.1%, beam diameter containing dose > 80% of the central axis was 10.6 cm and 9.6 cm, and symmetry (defined as the maximum dose difference between any two symmetric points about the central axis in the flat portion of the beam, as a percentage of central dose) was 2.24% and 2.20%. PDD values for the cone-less set-up at Dmax, R95, R85, and R50 were, respectively, 3.1, 4.1, 5.3, and 6.8 cm. <h3>Conclusion</h3> We have developed a novel cone-less set-up that allows for the delivery of electron FLASH-RT utilizing a clinical LINAC at practical SSDs and verified that its beam profiles are clinically feasible. Further work will be done to characterize additional SSDs and field sizes, along with the addition of a custom skin collimator to further shape the beam. This will pave the way for practical treatment using electron FLASH-RT to a host of oncologic indications, including cutaneous malignancies and partial breast irradiation in the future.

A tarsal spinning organ in glomeridesmid millipedes (Diplopoda: Pentazonia: Glomeridesmida)

Abstract The production of sticky threads from spinnerets is known from various myriapod groups including some representatives of the millipedes (Diplopoda). In Diplopoda the thread-producing glands are mostly seta-like and positioned terminally on the telson, and the secretion product is typically used to build molting chambers or egg sacs. So far, no such secretions or organs have been documented for the subgroup Pentazonia. Here we describe thread-producing glands from the species-poor Glomeridesmida. These putative spinning organs are single circular fields of small pores (spinning fields) positioned on the outer side of the tarsi of all walking legs of mature and juvenile individuals of both sexes. These pores are the openings of cuticular tubuli (conducting canals), which extend from the tarsus to an aggregation of cells, a putative gland, within the femur. In several specimens thin threads were observed to be extruded from the pores. The tarsal spinning fields are present in all 21 investigated Glomeridesmida morphospecies, including Termitodesmidae and Glomeridesmidae from South East Asia, the Indian subcontinent, Oceania, and South and Central America. These organs might constitute an apomorphic character of the Glomeridesmida, as similar organs are absent in other Myriapoda. The function of the extruded threads in Glomeridesmida remains speculative, because observations of living specimens of the group are almost non-existing. We suggest that the secretion might be used for defense, to build molting chambers or to secure tunnels burrowed in the substrate.