Transverse Extent Research Articles

Observation of the topological aberrations of twisted light

When reflected from an interface, a laser beam generally drifts and tilts away from the path predicted by ray optics, an intriguing consequence of its finite transverse extent. For twisted light, such beam shifts manifest even more dramatically: upon reflection, a field containing a high-order optical vortex is expected to experience not only geometrical shifts, but an additional splitting of its high-order vortex into a constellation of unit-charge vortices, a phenomenon known as topological aberration. In this article, we report on the experimental observation of the topological aberration effect, verified through the deformation of vortex constellations upon reflection. We develop a general theoretical framework to study topological aberrations in terms of the elementary symmetric polynomials of the coordinates of a vortex constellation, a mathematical abstraction which we prove to be the physical quantity of practical interest.

Robust Majorana bound states in magnetic topological insulator nanoribbons with fragile chiral edge channels

Magnetic topological insulators in the quantum anomalous Hall regime host ballistic chiral edge channels. When proximitized by an s-wave superconductor, these edge states offer the potential for realizing topological superconductivity and Majorana bound states without the detrimental effect of large externally applied magnetic fields on superconductivity. Realizing well-separated unpaired Majorana bound states requires magnetic topological insulator ribbons with a width of the order of the transverse extent of the edge state, however, which is expected to bring the required ribbon width down to around 100nm. In this regime, it is known to be extremely difficult to retain the ballistic nature of chiral edge channels and realize a quantized Hall conductance. In this paper, we study the impact of disorder in such magnetic topological insulator nanoribbons and compare the fragility of ballistic chiral edge channels with the stability of Majorana bound states when the ribbon is covered by a superconducting film. We find that the Majorana bound states exhibit greater robustness against disorder than the underlying chiral edge channels. Published by the American Physical Society 2024

Comparison of Furlow and Straight-Line Repair Techniques on Transverse Dental Arch Dimensions and Extent of Orthodontic Intervention

Comparison of Furlow and Straight-Line Repair Techniques on Transverse Dental Arch Dimensions and Extent of Orthodontic Intervention

28. Comparison of Furlow and Straight Line Repair Techniques on Transverse Dental Arch Dimensions and Extent of Orthodontic Intervention

PURPOSE: While the Furlow and straight line repair are the most commonly performed palatoplasty techniques, studies have advocated for the Furlow technique as it provides an increase in palatal lengthening. However, the Furlow technique’s impact on the transverse axis of the dental arch has yet to be explored. This study aims to compare the impact of the Furlow and straight line repair techniques on the transverse dental arch dimensions and the extent for postoperative orthodontic interventions. METHODS: A retrospective chart review of patients with cleft palate with or without a cleft lip at an urban pediatric medical center receiving care from senior surgeons between 1997-2022 was completed. Variables including cleft characteristics, repair type, and orthodontic evaluation and interventions were collected. Patients undergoing straight line repairs (SLR) were compared to those undergoing Furlow palatoplasty. Data were analyzed using Wilcoxon and Chi-Squared analyses in R Studio 4.2.1. RESULTS: Of 1,552 patients with cleft lip and palate deformities, 53% underwent Furlow repair and 47% underwent SLR. SLR was associated with increased rates of maxillary narrowing (orthodontist reported) when compared to Furlow repairs (47% vs 33%, p=.013). Additionally, patients undergoing SLR demonstrated higher rates of orthodontic transverse palatal expansion compared to the Furlow cohort (45.88% vs 30.19%, p=.002). Sub-analysis by cleft type demonstrated that this relationship was only maintained in Veau IV clefts and not in Veau I-III, where the repair technique did not influence rates of transverse palatal expansion. CONCLUSION: This data associates SLR with increased prevalence of maxillary narrowing and transverse palatal expansion, particularly in veau IV cleft phenotypes. A potential explanation is that the greater width of bilateral clefts may require more extensive dissection, contributing to increased scarring and transverse maxillary hypoplasia when completing straight line repair. When counseling patients and families on benefits of various repair techniques, Veau IV clefts should be advised that more extensive orthodontic interventions may be required with straight line repair techniques.

D48. Comparison of Furlow and Straight-line Repair Techniques on Transverse Dental Arch Dimensions and Extent of Orthodontic Intervention

PURPOSE: The Furlow and straight-line repair are commonly performed palatoplasty techniques. The impact of palatoplasty technique on the transverse axis of the dental arch has yet to be explored. This study aims to compare the impact of palatoplasty techniques on the transverse palatal dimensions and the extent for postoperative orthodontic interventions. METHODS: A retrospective chart review of all patients with cleft palate at an urban academic institution between 1997-2022 was completed. Variables including cleft phenotype, repair type, and orthodontic evaluation and interventions were collected. Data were analyzed using Wilcoxon and Chi-Squared analyses in RStudio 4.2.1. RESULTS: 1,552 patients with cleft palate deformities, 53% underwent Furlow repair and 47% underwent straight line repair. Straight line repairs were associated with increased rates of orthodontist reported maxillary narrowing compared to Furlow (47% vs 33%, p=.013). Additionally, patients undergoing straight line repair demonstrated higher rates of orthodontic transverse palatal expansion compared to the Furlow cohort (45.88% vs 30.19%, p=.002). Sub-analysis demonstrated this relationship was only maintained in Veau IV clefts and not in Veau I-III, where the repair technique did not statistically affect rates of transverse palatal expansion. CONCLUSION: This data associates straight line repair with increased prevalence of maxillary narrowing and transverse palatal expansion, particularly in Veau IV cleft phenotypes. Independent of the soft palate repair technique, hard palate repair is relatively standardized. These results implicate the soft palate repair method may affect maxillary development and subsequent orthodontic needs in patients with bilateral cleft lip and palate.

Beam optics study for a potential VHEE beam delivery system

VHEE (Very High Energy Electron) therapy can be superior to conventional radiotherapy for the treatment of deep seated tumours, whilst not necessarily requiring the space and cost of proton or heavy ion facilities. Developments in high gradient RF technology have allowed electrons to be accelerated to VHEE energies in a compact space, meaning that treatment could be possible with a shorter linac. A crucial component of VHEE treatment is the transfer of the beam from accelerator to patient. This is required to magnify the beam to cover the transverse extent of the tumour, whilst ensuring a uniform beam distribution. Two principle methodologies for the design of a compact transfer line are presented. The first of these is based upon a quadrupole lattice and optical magnification of beam size. A minimisation algorithm is used to enforce certain criteria on the beam distribution at the patient, defining the lattice through an automated routine. Separately, a dual scattering-foil based system is also presented, which uses similar algorithms for the optimisation of the foil geometry in order to achieve the desired beam shape at the patient location.

Computational analysis of experiments on shock detachment in hypersonic flow of nitrogen and carbon dioxide over a wedge

One of the most dramatic effects of vibrational and chemical non-equilibrium in hypersonic flows occurs in the bow-shock detachment process in flow over a wedge. This was shown theoretically and in reflected shock tunnel experiments by Hornung & Smith (J. Fluid Mech., vol. 93, 1979, pp. 225–239). In the present work, the effect is first demonstrated by computation of two-dimensional non-equilibrium flows. The effect of the finite transverse extent of the wedge is then studied by three-dimensional computations of non-relaxing flows. An analytical formula is obtained that gives the shock detachment distance of a finite wedge for ideal-gas and equilibrium flows. In the experiment, the finite transverse extent of the wedge competes with the non-equilibrium effects, as each introduces a new length scale. The carbon dioxide and nitrogen flows of the experiment are therefore computed in three dimensions and with two-temperature chemistry accounting for vibrational and chemical non-equilibrium. In the case of nitrogen flow, the agreement between experiment and computation is not good, the experimental detachment distance being larger. A number of possible reasons are quantitatively examined. A conclusive resolution of the discrepancy is considered to require a repeat of the experiment with more accurately characterized conditions. In the case of the carbon dioxide experiments, the computed results agree remarkably well with experiment. This is partially due to the fact that the condition is very close to equilibrium, where the sensitivity of the detachment process to relaxation effects is small. The analytical expression for the dimensionless detachment distance agrees very well with all the three-dimensional computations of non-relaxing flows.

Presenting features of neuroblastoma with spinal canal invasion. A prospective study of the International Society of Pediatric Oncology Europe - Neuroblastoma (SIOPEN).

IntroductionBetween 5 and 15% of children with neuroblastoma (NB) present with or develop spinal canal invasion (SCI). The majority of these children have symptoms of epidural compression of spinal cord and/or spinal nerves. Treatment of NB-SCI is considered an emergency but its modalities are not yet well-established. Independently of treatment, NB-SCI may result in significant long-term disabilities. We report on the first prospective study of NB-SCI focused on presenting characteristics of both symptomatic and asymptomatic patients and correlation between SCI-related symptoms and imaging features.Materials and methodsThis SIOPEN prospective NB-SCI study opened in June 2014. Patient data including SCI symptoms evaluated by standardized measures and spinal cord imaging studies were collected for each patient. For the purpose of this study data entry was locked on July 2021.ResultsOf the 208 NB-SCI patients registered, 196 were evaluable for this analysis of whom 67% were symptomatic and 33% asymptomatic. Median age was 11 months. The thorax was the commonest primary tumor site. The median intervals between initial symptoms and diagnosis and between first medical visit and diagnosis were 14 and 3 days, respectively. The was no statistical difference in frequency of presenting characteristics between symptomatic and asymptomatic patients. Presenting features of NB-SCI patients differed from other NBs for older median age, prevalence of thoracic vs. abdominal primary site, prevalence of localized vs. metastatic disease and lower incidence of MYCN gene amplification. The most common SCI features were motor deficit in the younger and pain in the older patients that correlated on imaging with both transverse and longitudinal extent but not with the level of intraspinal tumor. Spinal cord T2-hyperintensity was more frequently detected in symptomatic patients (not significant).ConclusionThis prospective study confirms that children with NB-SCI differ from NBs without SCI. Compared to previous studies, it provides more detailed information regarding presenting symptoms, time intervals between SCI symptoms, medical visit and diagnosis, and correlations between symptoms and imaging features.

The effect of transverse wavefront width on specular neutron reflection.

In the analysis of neutron scattering measurements of condensed matter structure, it normally suffices to treat the incident and scattered neutron beams as if composed of incoherent distributions of plane waves with wavevectors of different magnitudes and directions that are taken to define an instrumental resolution. However, despite the wide-ranging applicability of this conventional treatment, there are cases, such as specular neutron reflectometry, in which the structural length scales of the scattering object require that the wavefunction of an individual neutron in the beam be described by a spatially localized packet - in particular with respect to the transverse extent of its wavefronts (i.e. normal to the packet's mean direction of propagation). It is shown in the present work that neutron diffraction patterns observed for periodic transmission phase gratings, as well as specular reflection measurements from patterned thin films with repeat units of the order of micrometres, can be accurately described by associating an individual neutron with a wave packet and treating a beam as a collection of independent packets. In these cases, accurate analysis requires that the transverse spatial extent of a neutron packet wavefront be accounted for in addition to the angular divergence of the beam that is characterized by a distribution of packet mean wavevector directions. It is shown how a measure of the effective transverse spatial extent of the neutron packet - over which its wavefronts are of sufficient uniformity to produce coherent scattering - can be determined by employing reference diffraction gratings and patterned thin films of known structure and composition.

Succinct Review Article on Male Sterility Diagnosis, Symptoms, and Treatment

Background: Interspecific hybrid male sterility is a common occurrence in nature and plays a vital role in species reproductive isolation. Recently several studies have suggested a decline in the quality of semen. About half of the infertile causes are in men; the rate increases in the infertile couples. Some therapy for male sterility; medication, surgery, or assisted reproductive technology (ART). Medicinal effects are not expected, and surgical cases are localized for indication. Moreover, since most male sterility is idiopathic insufficiency of spermatogenesis, a recent tendency in the male-sterile therapy is ART such as IVF-ET, ICSI, TESE, etc.
 In oncology and Graves' disease, retraction of the thyroid gland is implicated in the pathogenesis of destruction of the endocrine glands, extraneous division of the superior and inferior laryngeal nerves, collapsed lung associated with cardiovascular destruction, or the possibility of remnant glandular tissue is remaining. This research aimed to identify how common thyroid gland anomalies in anatomy and development are to reduce the risks of thyroid surgical problems. There were a total of 20 corpses dissected. The pyramidal lobe of the thyroid gland, the levator glandule thyroideae, or the half or total disappearance of the isthmus has all been investigated. The gland's right and left lobes were measured length, maximal transverse, and anteroposterior extent. The bulk of these anatomical discrepancies can be attributed to an organogenesis mistake. Thyroid dysgenesis comprises ectopic thyroid, hemiparesis, hemiagensis, hypoplasia, and anatomical abnormalities in the thyroid gland produced by improper organogenesis.

Basis of rational design of mineral wool product polymerization furnace on conveyor horizontal dryer

The structural features of the thermal unit for the production of molded heat insulation materials and their technological parameters must be in full compliance with the properties of the initial materials and are determined by the production program of the enterprise. Based on the peculiarities of gas dynamics formation, the structural parameters of the thermal chamber are determined: dimensions, shape of the internal surface, presence of longitudinal and transverse seals, extent and parameters of heat treatment. Method of thermal calculation including separate consideration of conditions of mineral wool carpet heating in heat chamber and formation of heat carrier flow in furnace is proposed.

Finite gyroradius multidimensional electron hole equilibria

Finite electron gyroradius influences on the trapping and charge density distribution of electron holes of limited transverse extent are calculated analytically and explored by numerical orbit integration in low to moderate magnetic fields. Parallel trapping is shown to depend upon the gyroaveraged potential energy and to give rise to gyroaveraged charge deficit. Both types of average are expressible as convolutions with perpendicular Gaussians of width equal to the thermal gyroradius. Orbit-following confirms these phenomena but also confirms for the first time in self-consistent potential profiles the importance of gyrobounce resonance detrapping and consequent velocity diffusion on stochastic orbits. The averaging strongly reduces the trapped electron deficit that can be sustained by any potential profile whose transverse width is comparable to the gyroradius rg. It effectively prevents equilibrium widths smaller than ∼rg for times longer than a quarter parallel-bounce-period. Avoiding gyrobounce resonance detrapping is even more restrictive, except for very small potential amplitudes, but it takes multiple bounce periods to act. Quantitative criteria are given for both types of orbit loss.

Rotational effects on exchange flows across a submerged sill

This paper presents new laboratory-scale numerical simulations of density-driven exchange flows generated across an idealised, submerged sill obstruction under both non-rotating and rotating frames of reference using the Bergen Ocean Model (BOM), a three-dimensional general ocean circulation model. Initial non-rotating BOM simulations are compared directly with previous laboratory data obtained in a large-scale channel facility incorporating an idealised trapezoidal sill. These laboratory experiments demonstrate that the saline intrusion flux across the sill is initially reduced and then eventually fully blocked under increasing net-barotropic flow conditions imposed in the counterflowing upper freshwater layer, with the saline blockage also more evident for reduced sill submergence depths. These parametric dependences are also demonstrated in the equivalent BOM simulations of the non-rotating sill exchange flows, although the numerical model results tend to overpredict both the interfacial velocity and density gradients across the sill (as indicative of suppressed interfacial mixing), as well as the fresh-saline source flux ratio at which full blockage of the saline intrusion occurs. The BOM simulations are then extended to consider rotating sill exchange flow dynamics. In particular, these additional runs demonstrate that Coriolis forces increase the overall blockage of the saline intrusion layer compared to equivalent non-rotating exchange flows, especially when the Rossby number associated with the saline intrusion flow across the sill is considerably less than unity. This effect is largely attributed to the development of Ekman boundary layer dynamics and associated secondary circulations within the bi-directional exchange flows. These are shown to impose strong control on the transverse distribution and extent of the lower saline intrusion flow across the sill and, hence, the parametric conditions under which full saline intrusion blockage is achieved in rotating sill exchange flows.

Oblate electron holes are not attributable to anisotropic shielding

The influence of shielding mechanisms on the ratio of perpendicular to parallel scale lengths of multidimensional plasma electron hole equilibria is analyzed theoretically and computationally. It is shown that the “gyrokinetic” model, invoking perpendicular polarization, is based on a misunderstanding and cannot explain the observational trend that greater transverse extent accompanies a lower magnetic field. Instead, the potential in the wings of the hole, outside the region of trapped-electron depletion, has isotropic shielding giving ϕ∝e−r/L/r, with the shielding length L equal to the Debye length for holes much slower than the electron thermal speed. Particle in cell simulations confirm the analysis. Trapped electron charge distribution anisotropy must, therefore, instead underlie the oblate shape of electron holes.

Cosine beam: diffraction-free propagation and self-healing.

In this paper we revisit the nondiffracting properties of the cosine beam (CB). Since the CB is of infinite extension and not physically realizable, we use two apodization pupils to manage its transverse extent: the first one is a Gaussian apodized pupil, giving rise to the cosine-Gauss (CG) beam, and the second one is a window (aperture) apodized pupil, giving rise to the cosine-windowed beam. Based on the second-order intensity moments, we demonstrate analytical expressions for the CG beam width and its nondiffracting range as a function of some key parameters. By considering the CG beam a standing wave resulting from the superposition of two oppositely oblique traveling Gaussian beams, we extend the study to higher-order CG beams. The latter is generated by the superposition of two oppositely oblique Hermite-Gauss (HGn) beams of order n, giving birth to a standing nondiffracting Hermite-cosine-Gauss (HCGn) beam of order n. We also demonstrate the expressions of the higher-order CG beam width and its nondiffracting range zmax. After demonstrating the nondiffracting nature of the HCG beam family, we test their ability to self-heal and recover against obstacles, and we show the limit distance from which HCGn beams self-heal as a function of obstruction size and CG parameter. The results of this paper are of big interest in fields involving structured light such as particle manipulation, imaging, and light sheet microscopy.

An [O iii] search for extended emission around AGN with H i mapping: a distant cloud ionized by Mkn 1

ABSTRACT Motivated by the discovery of large ionized clouds around AGN, and particularly the large fraction of those that are consistent with photoionized gaseous tidal debris, we searched for [O iii] emission around Seyfert galaxies previously mapped in H i, many with extended gas features. Of 26 Seyfert galaxies, we find one spatially extended emission feature, a discrete cloud projected ≈12 kpc SW from the centre of Mkn 1 and spanning a transverse extent of 8 kpc. Optical spectroscopy (Kast/Lick and SCORPIO/BTA) of this cloud confirms its association with the Mkn 1–NGC 451 galaxy pair, closely matching the kinematics of nearby H i structures, and reveals emission-line ratios requiring photoionization by the AGN at roughly the direct observed luminosity of the nucleus. For the entire sample, the full opening angle of the ionization cones (bicones) must be <20° if the AGNs are continuously bright for scales longer than the light-traveltimes to the H i structures. Since typical AGN ionization cones are observed to be much broader than this, our low detection fraction may add to evidence for the ubiquity of strong variations in AGN luminosity on scales 104–105 yr.

Focal extent of scalar beams

The Andrejic focal extent measures, based on intensity, are an effective area in the focal plane, and an effective length of the focal region. The Cauchy–Schwartz inequality then provides lower bounds for both the transverse and longitudinal extents. Two families of monochromatic scalar beams, which share a tight-focus limit, are compared in their transverse and longitudinal focal extents. Both the beam families are characterized by a dimensionless parameter where is the wavenumber, and is a length. As increases from zero the transverse and longitudinal extents of both families increase monotonically. For large , the longitudinal extent becomes proportional to the length and the transverse localization is the same as for the Gaussian beam. For small , the two families have a confluent limit, the proto-beam. The Andrejic transverse extent lower bound is reached by the proto-beam, but the longitudinal extent lower bound is exceeded by the factor A hypothetical beam which reaches the longitudinal extent lower bound is shown to be non-physical.

Mechanical basis for thermonastic movements of cold-hardy Rhododendron leaves.

The profusion of rhododendrons in cold climates is as remarkable as the beauty of their blooms. The cold-hardiness of some of the montane species is in part due to reversible leaf movements triggered under frigid conditions wherein the leaves droop at the leaf stalks (petioles) and their margins roll up around the midrib. We probe the mechanics of these movements using leaf dissection studies that reveal that the through-thickness differential expansion necessary for leaf rolling is anisotropically distributed transverse to and along the midrib. Numerical simulations and theoretical analyses of bilayer laminae show that the longitudinal expansion amplifies the transverse rolling extent. The curvature diversion scales with the in-plane Poisson's ratio, suitably aided by the stiff midrib that serves as a symmetry breaking constraint that controls the competition between the longitudinal and transverse rolling. Comparison of leaf rolling with and without the petiole indicates that the petiole flexibility and leaf rolling are in part mechanically coupled responses, implicating the hydraulic pathways that maintain the critical level of midrib stiffness necessary to support the longitudinal expansion. The study highlights the importance of curvature diversion for efficient nastic and tropic leaf movements that enhance cold-hardiness and drought resistance, and for morphing more general hinged laminae.

Transverse extent of numerical model for deep buried tunnel excavation

Numerical simulation has been widely used for predicting rock mass convergence during tunnel excavation. Considering that tunnel construction is a three-dimensional (3D) process, the 3D numerical analysis, instead of the plane-strain models, are commonly employed in engineering practice. As the 3D numerical analyses require large numbers of computational resources, the geometric extents are often kept to a minimum to reduce simulation time. However, there is a lack of published information concerning appropriate the size of numerical model. The study investigates how the transverse range of tunnel section, including the upper boundary, the lower boundary and the lateral boundary, affects the tunnel convergence via the finite difference software package FLAC3D, respectively. Then, a comprehensive function to yield the minimum transverse section area within a given error is proposed. After several cases with different categories of rock are employed in the simulations, the universal model extents with the minimum transverse section area are proposed.

Clinical Application of Diagnostic Imaging of Chiari-Like Malformation and Syringomyelia.

Chiari-like malformation (CM) and syringomyelia (SM) is a frequent diagnosis in predisposed brachycephalic toy breeds since increased availability of MRI. However, the relevance of that MRI diagnosis has been questioned as CM, defined as identification of a cerebellar herniation, is ubiquitous in some breeds and SM can be asymptomatic. This article reviews the current knowledge of neuroanatomical changes in symptomatic CM and SM and diagnostic imaging modalities used for the clinical diagnosis of CM-pain or myelopathy related to SM. Although often compared to Chiari type I malformation in humans, canine CM-pain and SM is more comparable to complex craniosynostosis syndromes (i.e., premature fusion of multiple skull sutures) characterized by a short skull (cranial) base, rostrotentorial crowding with rostral forebrain flattening, small, and ventrally orientated olfactory bulbs, displacement of the neural tissue to give increased height of the cranium and further reduction of the functional caudotentorial space with hindbrain herniation. MRI may further reveal changes suggesting raised intracranial pressure such as loss of sulci definition in conjunction with ventriculomegaly. In addition to these brachycephalic changes, dogs with SM are more likely to have craniocervical junction abnormalities including rostral displacement of the axis and atlas with increased odontoid angulation causing craniospinal junction deformation and medulla oblongata elevation. Symptomatic SM is diagnosed on the basis of signs of myelopathy and presence of a large syrinx that is consistent with the neuro-localization. The imaging protocol should establish the longitudinal and transverse extent of the spinal cord involvement by the syrinx. Phantom scratching and cervicotorticollis are associated with large mid-cervical syringes that extend to the superficial dorsal horn. If the cause of CSF channel disruption and syringomyelia is not revealed by anatomical MRI then other imaging modalities may be appropriate with radiography or CT for any associated vertebral abnormalities.