Well-defined Limits Research Articles

Asymptotics of spin-0 fields and conserved charges on n-dimensional Minkowski spaces

We use conformal geometry methods and the construction of Friedrich's cylinder at spatial infinity to study the propagation of spin-0 fields (solutions to the wave equation) on n-dimensional Minkowski spacetimes in a neighbourhood of spatial and null infinity. We obtain formal solutions written in terms of series expansions close to spatial and null infinity and use them to compute non-trivial asymptotic spin-0 charges. It is shown that if one examines the most general initial data within the class considered in this paper, the expansion is polyhomogeneous and hence of restricted regularity at null infinity. Furthermore, we derive the conditions on the initial data needed to obtain well-defined limits for the asymptotic charges at the critical sets where null infinity and spatial infinity meet. In four dimensions, we find that there are infinitely many well-defined asymptotic charges at the critical sets, while for higher dimensions there is only a finite number of non-trivial asymptotic charges with well-defined limits at the critical sets.

Phonon screening and dissociation of excitons at finite temperatures from first principles

The properties of excitons, or correlated electron-hole pairs, are of paramount importance to optoelectronic applications of materials. A central component of exciton physics is the electron-hole interaction, which is commonly treated as screened solely by electrons within a material. However, nuclear motion can screen this Coulomb interaction as well, with several recent studies developing model approaches for approximating the phonon screening of excitonic properties. While these model approaches tend to improve agreement with experiment, they rely on several approximations that restrict their applicability to a wide range of materials, and thus far they have neglected the effect of finite temperatures. Here, we develop a fully first-principles, parameter-free approach to compute the temperature-dependent effects of phonon screening within the ab initio [Formula: see text]-Bethe-Salpeter equation framework. We recover previously proposed models of phonon screening as well-defined limits of our general framework, and discuss their validity by comparing them against our first-principles results. We develop an efficient computational workflow and apply it to a diverse set of semiconductors, specifically AlN, CdS, GaN, MgO, and [Formula: see text]. We demonstrate under different physical scenarios how excitons may be screened by multiple polar optical or acoustic phonons, how their binding energies can exhibit strong temperature dependence, and the ultrafast timescales on which they dissociate into free electron-hole pairs.

Uterine Niche: A Pathology to Consider

Uterine niche is a recess located in the anterior wall of the uterine isthmus, over the cesarean section scar. This condition is often asymptomatic, but it can be associated with symptoms such as abnormal uterine bleeding, pelvic pain and secondary infertility. Endovaginal ultrasound is the first-line diagnostic method. Treatment includes hormonal methods or surgery, and surgical treatment seems to be the most effective in resolving symptoms. We describe the case of a 37-year-old woman, with an obstetric history of a pregnancy with cesarean delivery, who complained of pelvic pain and menstrual irregularity. An endovaginal ultrasound was requested, which reported the presence of a “… echogenic oval formation with well-defined limits measuring 28x17 mm in the topography of the cesarean scar.” After a clinical discussion with a doctor specializing in Gynecology, the patient was referred to a hospital consultation in this specialty for investigation. The diagnosis of uterine niche was confirmed, and the treatment consisted of the placement of an intrauterine system.

Constructing condensed memories in functorial time

ABSTRACT If episodic memory is constructive, experienced time is also a construct. We develop an event-based formalism that replaces the traditional objective, agent-independent notion of time with a constructive, agent-dependent notion of time. We show how to make this agent-dependent time entropic and hence well-defined. We use sheaf-theoretic techniques to render agent-dependent time functorial and to construct episodic memories as sequences of observed and constructed events with well-defined limits that maximise the consistency of categorisations assigned to objects appearing in memories. We then develop a condensed formalism that represents episodic memories as pure constructs from single events. We formulate an empirical hypothesis that human episodic memory implements a particular time-symmetric constructive functor, and discuss possible experimental tests.

On new results on extremal graph theory, theory of algebraic graphs, and their applications

New explicit constructions of infinite families of finite small world graphs of large girth with well-defined projective limits which is an infinite tree are described. The applications of these objects to constructions of LDPC codes and cryptographic algorithms are shortly observed. We define families of homogeneous algebraic graphs of large girth over the commutative ring K. For each commutative integrity ring K with |K| > 2, we introduce a family of bipartite homogeneous algebraic graphs of large girth over K formed by graphs with sets of points and lines isomorphic to Kn, n > 1, and cycle indicator ≥ 2n + 2 such that their projective limit is well defined and isomorphic to an infinite forest.

SURGICAL TREATMENT OF CALCIFYING ODONTOGENIC CYST—CASE REPORT

An 18-year-old male patient reporting swelling in the mouth was referred to the oral and maxillofacial surgery service. On intraoral examination, the presence of a bulge along the bottom of the posterior right mandibular vestibule was noted, with normal color and a smooth surface. Panoramic radiographic examination revealed a multilocular radiolucent intraosseous lesion, with well-defined limits and radiopaque structure inside. Cone beam computed tomography showed root apices resorption of teeth 45, 46, and 47; expansion of the buccal and lingual cortical bone; and close contact of the lesion with the inferior alveolar vasculature-nervous bundle. Incisional biopsy revealed a calcifying odontogenic cyst. Surgical treatment was performed through enucleation, followed by curettage of the intraosseous lesion, under general anesthesia. The 1-year postoperative follow-up showed complete bone regeneration and there were no signs of recurrence. An 18-year-old male patient reporting swelling in the mouth was referred to the oral and maxillofacial surgery service. On intraoral examination, the presence of a bulge along the bottom of the posterior right mandibular vestibule was noted, with normal color and a smooth surface. Panoramic radiographic examination revealed a multilocular radiolucent intraosseous lesion, with well-defined limits and radiopaque structure inside. Cone beam computed tomography showed root apices resorption of teeth 45, 46, and 47; expansion of the buccal and lingual cortical bone; and close contact of the lesion with the inferior alveolar vasculature-nervous bundle. Incisional biopsy revealed a calcifying odontogenic cyst. Surgical treatment was performed through enucleation, followed by curettage of the intraosseous lesion, under general anesthesia. The 1-year postoperative follow-up showed complete bone regeneration and there were no signs of recurrence.

MULTIPLES ODONTOGENIC KERATOCYST IN TWO CHILDREN (BROTHER AND SISTER): CASE REPORT

The aim of these study was to describe a clinical case of a brother, 13 years old, and sister, 11 years old, who reported purulent drainage in the posterior region of the mandible. Imaging exams showed multiples radiolucent lesions, bilateral, with well-defined limits, located at the anterior region, body, angle of the mandible, and posterior region of the maxilla. Many included teeth were seen in the imaging exams. The diagnostic hypotheses were odontogenic keratocyst related to Gorlin-Goltz syndrome. Surgical decompression was performed, and the histopathologic analysis confirmed the diagnosis of odontogenic keratocyst. The father reported that he had previously undergone surgery to remove a mandibular lesion but did not remember the diagnosis. The investigation of Gorlin-Goltz syndrome is still being performed. The children are in follow-up and lesions will be enucleated after reduction in the lesions’ size. The aim of these study was to describe a clinical case of a brother, 13 years old, and sister, 11 years old, who reported purulent drainage in the posterior region of the mandible. Imaging exams showed multiples radiolucent lesions, bilateral, with well-defined limits, located at the anterior region, body, angle of the mandible, and posterior region of the maxilla. Many included teeth were seen in the imaging exams. The diagnostic hypotheses were odontogenic keratocyst related to Gorlin-Goltz syndrome. Surgical decompression was performed, and the histopathologic analysis confirmed the diagnosis of odontogenic keratocyst. The father reported that he had previously undergone surgery to remove a mandibular lesion but did not remember the diagnosis. The investigation of Gorlin-Goltz syndrome is still being performed. The children are in follow-up and lesions will be enucleated after reduction in the lesions’ size.

ODONTOGENIC KERATOCYST IN THE MAXILLA: CASE REPORT

A 32-year-old female patient was referred to the oral and maxillofacial surgery service with pain in the jaw for approximately 1 year. On extraoral and intraoral examination, there were no apparent changes or asymmetry. Cone beam computed tomography evidenced an extensive cystic lesion in the left maxillary bone, hypodense, with well-defined limits, extending to the maxillary sinus and involving the impacted tooth 28. Surgical treatment was performed under general anesthesia through enucleation followed by curettage of the entire lesion and removal of the involved impacted tooth. Histopathologic analysis of the specimen resulted in the diagnosis of odontogenic keratocyst. At 10-day follow-up, the surgical site showed adequate tissue repair process. In the postoperative clinical and radiographic follow-up at 1 year and 2 months, a complete bone regeneration was observed and there was no signs of lesion recurrence.

DIAGNOSIS, TREATMENT, AND FOLLOW-UP OF MINOR SALIVARY GLAND CANCER IN A YOUNG PATIENT

Mucoepidermoid carcinoma is the most common subtype of salivary gland malignancy and displays distinct histological features. A 17-year-old female patient, with nothing noteworthy in her medical history, was referred to our service for evaluation of a lesion located on the palate. According to the patient, the lesion appeared 4 months prior to consultation. Intraoral examination showed a purplish nodule on the right side of the hard palate measuring 1 × 1 cm, with a fibroelastic consistency and painful symptoms. Computed tomography revealed a nodular lesion with well-defined limits and absence of bone involvement. A biopsy was performed, and histopathologic examination revealed a cystic structure with mucus-secreting and epidermoid cells, characterizing a mucoepidermoid carcinoma. The patient was treated by surgical excision under general anesthesia and is being followed by our team. At 12-month follow-up, she is in good general health and has no evidence of tumor recurrence.

SCHWANNOMA OF UNUSUAL LOCATION IN ORAL CAVITY: CASE REPORT

A 22-year-old female patient reported edema on the floor of the mouth, without painful symptoms. The patient's medical history included systemic arterial hypertension. In the oral cavity, there was an increase in volume, firm on palpation, located on the right floor of the mouth, measuring approximately 4.0 × 3.0 cm, with well-defined limits, coloration similar to the normal mucosa, with evolution of 1 year and episodes of partial regression. Panoramic radiography, occlusal radiography, and ultrasound of the region showed no changes. Incisional biopsy was performed with a diagnostic hypothesis of a ranula. In the histopathologic analysis, sections stained with hematoxylin and eosin revealed a benign lesion of loose connective tissue slightly myxoid, suggesting mucocele (with possible fibrosis) or myxoma. Total surgical excision was performed under local anesthesia and the new histopathology was conclusive for schwannoma. The patient is being followed up and after 6 months there are no signs of recurrence of the lesion.

ORAL LEUKOPLAKIA IN A SMOKING PATIENT USING INHALED FORMOTEROL AND BUDESONIDE

A 67-year-old non-White female patient was referred to our service for evaluation of a white oral lesion. The patient reported being a heavy smoker for 56 years and a 15-year history of asthma controlled with inhaled formoterol fumarate and budesonide for 15 years. Extraoral examination showed no relevant alterations. Intraoral examination revealed a nondetachable white verrucous plaque on the right side of the soft palate close to the limit with the hard palate. The lesion measured approximately 1.5 × 1.0 cm and had regular borders and well-defined limits. The differential diagnosis included oral leukoplakia and verrucous carcinoma. A biopsy was performed under local anesthesia. Histologic examination revealed epithelium with hyperkeratosis, acanthosis, and an intense inflammatory reaction in the lamina propria, suggesting oral leukoplakia. The lesion was excised and the clinical and microscopic analyses confirmed the diagnosis of oral leukoplakia. No evidence of recurrence was observed at 19-month follow-up.

IN SITU ORAL MELANOMA: DIAGNOSIS, TREATMENT, AND FOLLOW-UP

Oral melanoma is an aggressive cancer in which the cells display melanocytic differentiation. In situ oral melanoma is considered an extremely rare tumor and the prognosis is poor compared to its cutaneous counterpart. A 67-year-old woman was referred for evaluation of a lesion on the maxillary alveolar mucosa. Intraoral examination revealed a nondetachable black patch on the maxillary alveolar mucosa extending to the hard palate with irregular borders and well-defined limits measuring 3 × 1.5 cm. A biopsy was performed, and microscopic analysis showed moderate atypical junctional melanocytic. Immunohistochemical analysis was positive for S-100, melan-A, and melanosome. The definitive diagnosis was in situ oral melanoma and the patient was treated surgically with partial maxillectomy. A definitive obturator prosthesis was made to provide effective rehabilitation. A 15-month follow-up showed no evidence of recurrence or metastasis. Oral melanoma is an aggressive cancer in which the cells display melanocytic differentiation. In situ oral melanoma is considered an extremely rare tumor and the prognosis is poor compared to its cutaneous counterpart. A 67-year-old woman was referred for evaluation of a lesion on the maxillary alveolar mucosa. Intraoral examination revealed a nondetachable black patch on the maxillary alveolar mucosa extending to the hard palate with irregular borders and well-defined limits measuring 3 × 1.5 cm. A biopsy was performed, and microscopic analysis showed moderate atypical junctional melanocytic. Immunohistochemical analysis was positive for S-100, melan-A, and melanosome. The definitive diagnosis was in situ oral melanoma and the patient was treated surgically with partial maxillectomy. A definitive obturator prosthesis was made to provide effective rehabilitation. A 15-month follow-up showed no evidence of recurrence or metastasis.

Toxicological impact of nanoparticles on human health: A review

Nanotechnology is a rapidly growing industry where nanomaterials are used in almost every field, including electronics, cosmetics, engineering, household products, biotechnology and medicine. Nanoparticles (NPs) have unique physical and chemical properties, which may cause potential hazards to human health, especially with constant exposure. Various studies have shown that NPs can enter the human body either through the respiratory tract, dermal absorption or via the gastrointestinal system and have the potential to cause respiratory disorders, behavioral changes, neurological disorders, as well as cancer. This review focuses on the health implications of NPs, specifically gold, silver, silica, titanium dioxide, aluminum, aluminum oxides, metal organic frameworks (MOF), aerosol particles, flame retardants, quantum dots, and carbon nanotubes. Herein, we discuss the routes of exposure and the impact of these nanoparticles on human health. We also summarize in-vitro and in-vivo studies that analyze the cytotoxicity profile and the associated health impact of these nanoparticles. This study could be utilized to develop well-defined guidelines for setting exposure limits for different NP types as well as a summary of related characteristics such as size, shape, morphology, and surface charge.

Estudo comparativo entre limites radiográfico e histológico em ameloblastomas

The aim of this study was to analyse the presence of histological infiltrations of neoplastic cells within the bone, and compare the distance of these infiltrations with the radiografic limits of the ameloblastoma. For this purpose, six integral surgical samples, with identifiable radiographic limits of the tumor, sent to the Pathology Service of Dental School of the Federal University of Rio Grande do SuÌ, were processed. From the resuÌts obtained, can be concluded úat, alúough ameloblastoma presents well-defined radiographic limits, it is infiltrative from the histological view point. Infiltrations occurs at few and distinctive sites. varying in this study from 0.10 cm to 1.40 cm, related to the radiographic borders of the neoplasm.

Hybrid odontogenic lesions: A systematic review of 203 cases reported in the literature.

Hybrid odontogenic lesions combine histopathological characteristics of two or more odontogenic cysts and/or tumours. The aim of this study was to evaluate the available data on hybrid odontogenic lesions (HOL) and to analyse their epidemiological/clinical features and biological behaviour. An electronic search was done in January 2021 using multiple databases. Eligibility criteria encompassed publications with sufficient clinical and histological information to confirm the tumours' diagnoses. A total of 147 articles were included in this study, comprising 203 cases. Calcifying odontogenic cyst associated with odontoma (COC/OD) (37/18.2%) was the most common HOL. Females were more affected with a mean age of 24.9years. Lesions presented as asymptomatic swellings, with a mean evolution time of 8.2months (0.3-96), and mean tumour size of 4.8cm (0.3-7). Radiographic aspects frequently showed radiolucent (139/68.4%) and unilocular (52/25.6%) images with well-defined limits (48/23.6%). The lesions mostly affected mandibular pre-molars (69/34%) and mandibular molars (69/34%) regions. Enucleation (89/43.8%) and surgical excision (59/29%) were the most common treatment modalities. The mean follow-up time was 33.8months (0.5-216months) and recurrences were observed in four cases (1.9%), all of which were central odontogenic fibroma associated with central giant cell granuloma (COF/CGCG). COC/OD is the most common HOL and recurrence is a rare event, being usually associated with the diagnosis of COF/CGCG.

Estudo comparativo entre limites radiográfico e histológico em ameloblastomas

The aim of this study was to analyse the presence of histological infiltrations of neoplastic cells within the bone, and compare the distance of these infiltrations with the radiografic limits of the ameloblastoma. For this purpose, six integral surgical samples, with identifiable radiographic limits of the tumor, sent to the Pathology Service of Dental School of the Federal University of Rio Grande do Sul, were processed. From the results obtained, can be concluded that, although ameloblastoma presents well-defined radiographic limits, it is infiltrative from the histological view point. Infiltrations occurs at few and distinctive sites, varying in this study from 0.10 cm to 1.40 cm, related to the radiographic borders of the neoplasm.

Phase-Separating Binary Polymer Mixtures: The Degeneracy of the Virial Coefficients and Their Extraction from Phase Diagrams.

The Edmond–Ogston model for phase separation in binary polymer mixtures is based on a truncated virial expansion of the Helmholtz free energy up to the second-order terms in the concentration of the polymers. The second virial coefficients (B11, B12, B22) are the three parameters of the model. Analytical solutions are presented for the critical point and the spinodal in terms of molar concentrations. The calculation of the binodal is simplified by splitting the problem into a part that can be solved analytically and a (two-dimensional) problem that generally needs to be solved numerically, except in some specific cases. The slope of the tie-lines is identified as a suitable parameter that can be varied between two well-defined limits (close to and far away from the critical point) to perform the numerical part of the calculation systematically. Surprisingly, the analysis reveals a degenerate behavior within the model in the sense that a critical point or tie-line corresponds to an infinite set of triplets of second virial coefficients (B11, B12, B22). Since the Edmond–Ogston model is equivalent to the Flory–Huggins model up to the second order of the expansion in the concentrations, this degeneracy is also present in the Flory–Huggins model. However, as long as the virial coefficients predict the correct critical point, the shape of the binodal is relatively insensitive to the specific choice of the virial coefficients, except in a narrow range of values for the cross-virial coefficient B12.

Lumbar Myelopathy Caused by Multiple Cartilaginous Exostoses in a Dog

A 6-months-old male mixed-breed dog was admitted to the veterinary hospital with lameness in the right pelvic limb, proprioceptive ataxia, and suspected spinal cord injury in the lumbosacral segment. Upon palpation, firm nodules were noted on the bony surface of the thoracic and pelvic limbs, ribs, vertebrae, and tail. The radiographic study showed nodules of low radiopacity with well-defined limits and smooth contours, one of which was overlapping the fifth lumbar vertebra. Given the clinical presentation indicative of spinal cord injury, the animal was subjected to hemilaminectomy for nodular resection. Histopathological examination of the biopsy enabled the diagnosis of osteochondroma. The clinical follow up after surgery showed improvement in walking, despite persistent monoparesis in the right pelvic limb. The radiographic study in association with clinical and histopathological exams allowed the diagnosis and monitoring of the lesions.

Infrared Problem vs Gauge Choice: Scattering of Classical Dirac Field

We consider the Dirac equation for the classical spinor field placed in an external, time-dependent electromagnetic field of the form typical for scattering settings: F=F^mathrm{ret}+F^mathrm{in}=F^mathrm{adv}+F^mathrm{out}, where the current producing F^{mathrm{ret}/mathrm{adv}} has past and future asymptotes homogeneous of degree -3, and the free fields F^{mathrm{in}/mathrm{out}} are radiation fields produced by currents with similar asymptotic behavior. We show the existence of the electromagnetic gauges in which the particle has ‘in’ and ‘out’ asymptotic states approaching free field states, with no long-time corrections of the free dynamics. Using a special Cauchy foliation of the spacetime, we show in this context the existence and asymptotic completeness of the wave operators. Moreover, we define a special ‘evolution picture’ in which the free evolution operator has well-defined limits for trightarrow pm infty ; thus the scattering wave operators do not need the free evolution counteraction.

Extensive central ossifying fibroma of mandible: case report

ABSTRACT A 34-year-old female patient attended a referral center for oral diagnosis presenting hardened increased volume in the posterior mandible. Panoramic radiography revealed a mixed unilocular lesion with clear and well-defined limits. The incisional biopsy showed proliferation of mesenchymal cells amid dense fibrous connective tissue. Mineralized material in different degrees of maturation was also observed. Regarding the histopathological aspects associated with the clinical, radiographic, and intraoperative data, the diagnosis of central ossifying fibroma (COF) was performed. COF has similar characteristics to other fibro-osseous lesions, and its diagnosis is a challenge for dental surgeons.