Weyl-mediated helical magnetism in NdAlSi.

Emergent relativistic quasiparticles in Weyl semimetals are the source of exotic electronic properties such as surface Fermi arcs, the anomalous Hall effect and negative magnetoresistance, all observed in real materials. Whereas these phenomena highlight the effect of Weyl fermions on the electronic transport properties, less is known about what collective phenomena they may support. Here, we report a Weyl semimetal, NdAlSi, that offers an example. Using neutron diffraction, we found a long-wavelength helical magnetic order in NdAlSi, the periodicity of which is linked to the nesting vector between two topologically non-trivial Fermi pockets, which we characterize using density functional theory and quantum oscillation measurements. We further show the chiral transverse component of the spin structure is promoted by bond-oriented Dzyaloshinskii-Moriya interactions associated with Weyl exchange processes. Our work provides a rare example of Weyl fermions driving collective magnetism.

Fractional topological insulators of Cooper pairs induced by the proximity effect.

Certain insulating materials with strong spin-orbit interaction can conduct currents along their edges or surfaces owing to the nontrivial topological properties of their electronic band structure. This phenomenon is somewhat similar to the integer quantum Hall effect of electrons in strong magnetic fields. Topological insulators analogous to the fractional quantum Hall effect are also possible, but have not yet been observed in any material. Here we show that a quantum well made from a topological band insulator such as Bi2Se3 or Bi2Te3, placed in contact with a superconductor, can be used to realize a two-dimensional topological state with macroscopic many-body quantum entanglement whose excitations carry fractional amounts of an electron's charge and spin. This fractional topological insulator is a "pseudogap" state of induced spinful p-wave Cooper pairs, a new strongly correlated quantum phase with possible applications to spintronic devices and quantum computing.

Root Resorptions on Adjacent Teeth Associated with Impacted Maxillary Canines.

AIM: Through the use of CBCT images, many unidentified features of impacted canines can be easily resolved. The potential collision of impacted maxillary canines and adjacent teeth could lead to root resorption (RR). The aim of this study is to examine the prevalence, location and severity of RR on adjacent teeth caused by impacted maxillary canines and the association between the adjacent teeth and the features of maxillary impacted canines on CBCT. METHODS: This study examined 89 subjects with 108 maxillary impacted canines, having had no previous orthodontic treatment (mean age: 18.3 ± 4.1 years). The following impacted-canine-related parameters were analyzed on the CBCT images: location; RR levels on adjacent teeth; occlusal line and midline distances of impacted canines; and the angulations of impacted canines to the midline, lateral incisor and occlusal line. Logistic regression was used to evaluate the association between RR and the measured parameters on CBCT. RESULTS: In this study, we found that the majority of our patients with impacted maxillary canines were female (62.5%). Of the total 108 maxillary impacted canines, 60.2% resorbed the adjacent teeth of the affected quadrants. Lateral incisors were the most affected (34.3%). The mean age of subjects with RR was 16.7 ± 3.5 years. The frequency of RR was statistically significantly higher in female subjects (40.4%). Slight RR was the most frequent (30.5%) and the highest incidence noted at the apical third of the root (29.6%). Regarding the impacted maxillary canine angulation to the midline and adjacent tooth, higher values of angulation caused severe forms of RR (p < 0.05). CONCLUSION: The sensitivity of CBCT allows for the accurate diagnosis of the location and the degree of RR, alongside the angulation and distance of impacted canines to adjacent teeth. The association between the linear and angular features of the impacted maxillary canines and RR was confirmed.

Pharyngeal Airway Changes after Bimaxillary Orthognathic Surgery--Preliminary Results.

INTRODUCTION: Dentofacial deformity, a deviation from normal facial proportions and dental relationships, is corrected by jaw repositioning in all three spatial planes, which changes the position and tension of the surrounding tissues, bones and muscles. These changes may also affect the dimensions of the pharyngeal airways (PA). OBJECTIVE: The aim of this study was to evaluate and compare three-dimensional PA changes in patients treated by a combination mandibular set-back/maxillary advancement versus patients that had bimaxillary advancement with genioplasty. METHODS: The sample consisted of 7 patients treated by combined mandibular set-back/maxillary advancement and 7 patients treated with bimaxillary advancement surgery. Nasopharyngeal (NP) volume, oropharyngeal (OP) volume and the area of maximum constriction (AMC) in the OP were measured on CBCT scans (2 mA/120 kV/12" FOV) taken before (T1) and 3 months after surgery (T2). Paired samples t-test was used for analyzing statistical significance of changes (p ≤ 0.05). RESULTS: OP volume and AMC increase after bimaxillary advancement was statistically significant, while for the mandibular set-back group the increase was non-significant. NP volume was not reduced in any of the two groups. No significant differences in PA dimensions were found between groups at neither T1 nor T2 time points. CONCLUSION: Results suggest that the combination of mandibular set-back/maxillary advancement did not reduce airway dimensions, while bimaxillary advancement surgery led to a statistically significant increase in the OP dimensions.

Charge and spin fractionalization in strongly correlated topological insulators.

We construct an effective topological Landau-Ginzburg theory that describes general SU(2) incompressible quantum liquids of strongly correlated particles in two spatial dimensions. This theory characterizes the fractionalization of quasiparticle quantum numbers and statistics in relation to the topological ground-state symmetries, and generalizes the Chern-Simons, BF ('background field') and hierarchical effective gauge theories to an arbitrary representation of the SU(2) symmetry group. We mainly focus on fractional topological insulators with time-reversal symmetry, which are treated as SU(2) generalizations of the quantum Hall effect.

Cephalometric assessment of maxillary length in Serbian children with skeletal class III.

BACKGROUND/AIM: Malocclusion of skeletal class III is a complex irregularity of sagittal inter-jaw relationship, which is due to irregularities of sagittal position of one or both of the jaw bones, which is often associated with disproportionate ratio of their length. The aim of this study was to determine whether the length of the jaw of children with skeletal class III in the period of mixed dentition was changed. METHODS: Fifty children with skeletal class III and the same number of those with skeletal class I, of both sexes, have been selected on the basis of cephalometric analysis of profile tele-x-ray of the head. All the children aged 6-12 had mixed dentition, and were divided according to sex and age into three subgroups within each group. The length of maxilla, mandible and cranial base were measured. Proportions among the lengths measured within each group were found and difference significance in the measured lengths and their proportions among groups and subgroups were evaluated. RESULTS: The children with skeletal class III, compared with the findings in the control group, had significantly lower values of maxillary length, total maxillary length, as well as lower values of their lengths in proportion to lengths of the front or the total length of cranial base and in proportion to mandibular lengths (p < 0.05). Among the patients of different sexes, both in the test and the control group, a significant difference in the values of the measured lengths was found. CONCLUSION: The children with skeletal class III have significantly shorter maxilla than those with skeletal class I.

Superconductivity at the border of electron localization and itinerancy.

The superconducting state of iron pnictides and chalcogenides exists at the border of anti-ferromagnetic order. Consequently, these materials could provide clues about the relationship between magnetism and unconventional superconductivity. One explanation, motivated by the so-called bad metal behaviour of these materials proposes that magnetism and superconductivity develop out of quasi-localized magnetic moments that are generated by strong electron-electron correlations. Another suggests that these phenomena are the result of weakly interacting electron states that lie on nested Fermi surfaces. Here we address the issue by comparing the newly discovered alkaline iron selenide superconductors, which exhibit no Fermi-surface nesting, to their iron pnictide counterparts. We show that the strong-coupling approach leads to similar pairing amplitudes in these materials, despite their different Fermi surfaces. We also find that the pairing amplitudes are largest at the boundary between electronic localization and itinerancy, suggesting that new superconductors might be found in materials with similar characteristics.

[Analysis of variation of sagittal position of the jaw bones in skeletal Class III malocclusion].

BACKGROUND/AIM: Skeletal Class III malocclusion is a discrepancy in the sagittal jaw relationship, due to imbalances in their development and/or position, resulting in the dominant appearance of the lower jaw in facial profile. The aim of this study was to determine variations in the sagittal position of the jaw bones to the cranial base in subjects with skeletal Class III, for the earliest possible diagnosis of malocclusion. METHODS: Fifty children and as many adults with skeletal Class III, both sexes, were examined and selected, based on the findings of sagittal interjaw relationship (ANB) < or = 0 degrees from the cephalometric analysis of tele-x-ray profile head shots. The subjects were grouped according to age. The first group consisted of children aged 6-12 years, and another group, of adults aged 18-26 years. We measured the angles of maxillary prognathism (SNA), mandibular prognathism (SNB) and ANB. Based on these results, within the respective groups subclassification into the subgroups was done, among which a significant difference measured values was evaluated. In both groups a significant correlation of the determined values was evaluated. RESULTS: An average SNA angle ranged 77.36 +/- 3.58 in children and 77.32 +/- 4.88 in adults, while an average SNB angle was 79.46 +/- 3.91 in the group of children and 81.12 +/- 3.76 in adults. An average ANB angle was -2.10 +/- 2.07 in children, and -4.00 +/- 2.34 in adults. In both groups, a significant correlation between the measured values and a significant difference in the values of all the measured parameters were found between patients from different subgroups (p < 0.01). CONCLUSION: The most common morphological variation of sagittal position of the upper jaw is its retrognatism, which is equally present in both children and adults. Sagittal position of the lower jaw in most of the adults was prognathic, while mandible prognathism in the children was less present.

Evaluation of a prevention programme efficiency for patients with fixed orthodontic appliances.

BACKGROUND/AIM: Orthodontic treatment enables the establishment of functional occlusion and improvement of oral health, however, it increases the risk of periodontal disease development. The aim of this paper was to examine the efficiency of the applied programme for the prevention of gingivitis in children undergoing the fixed orthodontic appliance therapy and to determine the most efficient devices and techniques for maintaining oral hygiene during orthodontic treatment. METHODS: The study included 80 patients of both genders--60 patients comprised the experimental group and 20 patients comprised the control group. All of them were patients of the Clinic for Orthodontics at the School of Dentistry in Belgrade, aged between 13 and 18. The Silness-Löe Plaque Index (PI) was utilised for the assessment of oral hygiene quality and Silness-Löe Gingival Index (GI) and Mühlemann Papilla Bleeding Index (PBI) were utilised for the assessment of gingival state. Checkups were conducted as a single-blind study at the beginning and after the first, the third and the sixth month of the preventive and prophylactic programme. RESULTS: During the observed period, a statistically significant change in PI, GI and PBI values was noticed (p < 0.005), as well as the difference in the dynamics of value changes during the periods between the observed groups. CONCLUSION: The preventive programme, applied to children undergoing the fixed orthodontic appliance therapy, had a positive effect both on oral hygiene quality and gingival state. The values of the examined parameters of the patients from the experimental group were significantly lower in comparison with those of the patients from the control group. The most efficient combination of devices for oral hygiene during orthodontic treatment was: a Curaprox CP5460 toothbrush, CD Ortho 60 orthodontic toothbrush and Curaprox CPS 14 interdental brush.

[Size of lower jaw as an early indicator of skeletal class III development].

BACKGROUND/AIM: Malocclusion of skeletal class III is a complex abnormality, with a characteristic sagital position of the lower jaw in front of the upper one. A higher level of prognatism of the lower jaw in relation to the upper one can be the consequence of its excessive length. The aim of this study was to find the differences in the length of the lower jaw in the children with skeletal class III and the children with normal sagital interjaw relation (skeletal class I) in the period of mixed dentition. METHODS: After clinical and x-ray diagnostics, profile tele-x-rays of the head were analyzed in 60 examinees with mixed dentition, aged from 6 to 12 years. The examinees were divided into two groups: group 1--the children with skeletal class III and group 2--the children with skeletal class I. The length of the lower jaw, upper jaw and cranial base were measured. The proportional relations between the lengths measured within each group were established and the level of difference in the lengths measured and their proportions between the groups were estimated. RESULTS: No significant difference between the groups was found in the body length, ramus and the total length of the lower jaw. Proportional relation between the body length and the length of the lower jaw ramus and proportional relation between the forward cranial base and the lower jaw body were not significantly different. A significant difference was found in proportional relations of the total length of the lower jaw with the total lengths of cranial base and the upper jaw and proportional relation of the length of the lower and upper jaw body. CONCLUSION: Of all the analyzed parameters, the following were selected as the early indicators of the development of skeletal class III on the lower jaw: greater total length of the lower jaw, proportional to the total lengths of cranial base and theupper jaw, as well as greater length of the lower jaw body, proportional to the length of the upper jaw body.

Superfluid-insulator transitions of the fermi gas with near-unitary interactions in a periodic potential.

We consider spin-1/2 fermions of mass m with interactions near the unitary limit. In an applied periodic potential of amplitude V and period a_{L}, and with a density of an even integer number of fermions per unit cell, there is a second-order quantum phase transition between superfluid and insulating ground states at a critical V=V_{c}. We compute the universal ratio V_{c}ma_{L};{2}/variant Planck's over 2pi;{2} at N=infinity in a model with Sp(2N) spin symmetry. The insulator interpolates between a band insulator of fermions and a Mott insulator of fermion pairs. We discuss implications for recent experiments.

[Radiographic cephalometry assessment of the linear and angular parameters on cranial base in children with skeletal class III].

BACKGROUND/AIM: In malocclusion of skeletal class III, mandible is located in front of maxilla in sagital plain, which is manifested by a lower value of the sagital inter-jaw angle than in skeletal class I, where the jaw sagital relation is normal. Apart from the deformities on mandible and/or maxilla, in skeletal class III deformities are also frequent on the cranial base. The aim of this research was to find the differences in the parameter values on the cranial base among the children with skeletal class III and the children with skeletal class I in the period of mixed dentition. METHODS: After clinical examination and orthopan-tomography, profile radiography of the head was analyzed in 60 examinees, aged from 6-12 years. The examinees were divided into two groups: group 1--the children with skeletal class III; group 2--the children with skeletal class I. Both linear and angular parameters on the cranial base were measured, as well as the angles of maxillary and mandible prognatism and the angle of sagital inter-jaw relation. The level of difference in the parameter values between the groups was estimated and the degree of correlation of the main angle of the cranial base with the angles of sagital position of the jaws in each of the two groups was established. RESULTS: A significant difference between the groups was found only in the average values of the angles of maxillary prognatism and sagital inter-jaw relation. In the group 1, the main angle of the cranial base was in a significant correlation with the angles of sagital positions of the jaws, while in the group 2, such significance was not found. CONCLUSION: There were no significant differences in the parameter values on the cranial base between the groups. There was a significant correlation of the main angle of the cranial base with the angles of sagital position of the jaws in the group 1 only.

[Effects of adenoidectomy and immediate orthodonthic treatment on jaw relations and naso-respiratory rehabilitation]. / Efekti adenoidektomije i neposrednog ortodontskog lecenja na uskladenost vilica i rehabilitaciju nazalne respiracije.

AIM: To determine if adenoidectomy itself could provide spontaneous relation of the transverse growth of jaws as well as an adequate mode of breathing or if there is a need for an additional orthodontic treatment to solve the problem. METHODS: The study included one hundred and one patients aged 6-17 yrs., divided into three groups: group K--patients with oral respiration caused by adenoidal enlargement; group 1--patients with adenoidectomy done 5 or more years before; group 2--patients with orthodontic treatment done immediately after adenoidectomy. Transverse occlusion relation, the frequency of crossbite, and the intensity of nasal respiration were measured in all three groups of patients. RESULTS: The obtained results have shown that in the patients with adenoidal enlargement and oral respiration, there was an evidence of maxillary width reduction as opposed to mandibular width. Of the patients, 14% were with unilateral or bilateral crossbite. In the patients with adenoidectomy done 5 or more years before, transverse maxillary growth compared to mandibular one in the region of the front width, showed statistically significant increase (p < 0.05) as opposed to the patients with adenoidal enlargement. The effect of adenoidectomy on transverse maxillary growth was not satisfactory anyway, which was also indicated by the increase of frequency of crossbite in 24% of the patients with adenoidectomy done 5 or more years before. In operated on and in the patients one month after orthodontic treatment, transverse maxillary growth compared to mandibular growth in all the regions of both front and back width, there was statistically highly significant increase (p < 0.01) as opposed to the patients with adenoidal enlargement and adenoidectomy done many years before. Significant maxillary and mandibular transverse relation was obtained without the presence of crossbite. Nasal respiration prevailled. CONCLUSION: Orthodontic therapy one month after adenoidectomy was necessary for solving the orthodontic problems caused by adenoidal enlargement and significantly contributed to the rehabilitation of nasal respiration.

Expression of the P2X7 receptor subunit of the adenosine 5'-triphosphate-gated ion channel in the developing and adult rat cochlea.

ATP-gated ion channels assembled from P2X(7) subunits have been implicated in ontogeny and cellular pathology. Here, the expression of the P2X(7) receptor subunit was studied in the embryonic (E14-E18 days) and postnatal (P0-adult) rat cochlea using immunohistochemistry. Strong P2X(7) immunolabelling was observed in the primary auditory neurons of the spiral ganglion from E18 to adult and in the fibres innervating the sensory inner and outer hair cells from birth to adult. Strong immunolabelling of P2X(7) receptor protein was also observed in the inner and outer hair cells over a limited developmental period, from birth to P6. Weak expression was observed in cochlear duct epithelium on E18 and in the supporting cells (footplates of pillar cells in adult and in Böttcher's cells after birth). The immunolocalisation of P2X(7) receptors further implicates extracellular ATP in signalling process in cochlear ontogeny and in establishment and function of auditory neurotransmission. The P2X(7) receptors may be involved in signal transduction and modulation as well as in regulating cell death during development and in pathological conditions.