Rashba-coupling modelling for two-dimensional and high-order Rashba Hamiltonian for one-dimensional confined heavy holes

Based on standard k.p (8 x 8) multiband Hamiltonian, we have deduced an explicit analytical expression for the Rashba-coupling parameter which clarifies its anomalous behavior for heavy holes (hh), gated in quasi-two-dimensional (Q2D) systems, by letting grow the density. Our modelling remarkable better agrees with experimental results in comparison with earlier theoretical models, while recovers the expected cubic dependence on the quasi-momentum. For quasi-one-dimensional (Q1D) hh systems, we have formally derived an effective Rashba Hamiltonian with two competitive terms on the quasi-momentum, a linear term and a cubic one as predicted from suitable approximations to the Q2D scope. The Rashba-coupling parameters also behave anomalously and qualitatively support recent experiments in core/shell nanowires. Furthermore, they exhibit an essential asymptotic discontinuity in the low density regime as a function of the lateral confinement length. For hh, we present closed schemes to accurately quote the Rashba-coupling parameters both for the Q2D and Q1D systems, which become unprecedented for holes.Comment: 6 pages, 4 figure

Malignant mental nerve neuropathy : systematic review

Malignant mental neuropathy (MMN) is a neurological manifestation of cancer, characterized by the presence of hypoesthesia or anesthesia restricted to the territory of the mental branch of the mandibular nerve. A systematic review of the literature has been made on MMN, analyzing the etiology, pathogeny, clinical characteristics, complementary tests and the prognosis. Sixteen studies, providing 136 cases were selected. Breast cancer and lymphomas were the most frequently associated malignant diseases. The most frequent pathogenic mechanisms producing neurological involvement were: peripherally, mandibular lesions; and centrally, tumors at the base of the cranium. Regarding clinical characteristics, manifestation of MMN was the primary symptom of malignant disease in 27.7% of cases, and a first symptom of recurrence in 37.7%. The group of selected studies included 50 orthopantomographs, 9 mandibular computed tomographies and 50 radiographic examinations of the cranial region. The most affected region was the mandible. The appearance of MMN is an ominous prognosis for the progression of the disease, with a mortality of 78.5% within a mean of 6.9 months

Studies on the electrochemical reduction and the photolysis of phenacyl 'onium salts and related compounds

The electrochemical reduction of a series of quaternary phenacyclammonium and tertiary phenacylsulphonium salts in aqueous solution at a mercury cathode has been investigated using polarography, coulometry, titrimetry and product analysis methods

Vestibular bone window for the extraction of impacted lower third molars : four case reports

Four patients attending for the extraction of an impacted lower third molar are reported. The aim of this paper is was to describe a technical approach, which facilitates impacted lower third molar extraction, minimizing the ostectomy, thus reducing secondary postoperative manifestations and avoiding possible periodontal defects on the distal side of the second mandibular molar. To facilitate the extraction of the crown, roots or the complete molar, a small ostectomy in the form of a window can be made in the vestibular cortical, approaching the extraction through the resultant mesial space

Influence of perforation of the sinus membrane on the survival rate of implants placed after direct sinus lift : literature update

The aim of this paper was to review the procedures adopted when a perforation of the sinus membrane takes place during a direct sinus lift for filling with bone graft; and the survival of implants in those cases in which perforation of the sinus membrane occurred. A bibliographical search in PUBMED was carried out of articles published from 1997 to 2008, with the key words ?sinus perforation? and ?membrane perforation?. All articles specifying the two following criteria were included: (a) procedure in the case of perforation of the sinus membrane during direct sinus lift; and (b) the number and survival rate of implants placed in direct sinus lift with perforated and non perforated membrane. Six articles fulfilled the inclusion criteria. In all the articles the sinus lift was continued when a perforation of the sinus membrane took place. In maxillary sinus lift procedures with perforation of the membrane a 88.6% implant survival rate was obtained, and in maxillary sinus lifts with intact membrane the survival rate rose to 98%. In case of small perforation of the sinus membrane, it is possible to continue with the procedure; there is no consensus on the procedure when a perforated membrane is to be repaired, but the method of choice according to the majority of authors is to use a resorbable membrane. In the case of large perforation, there is no consensus either, although the majority of authors choose to abandon the procedure. The survival of the implants diminishes when they are placed in sinus lifts with perforated membrane

Factors that influence the position of the peri-implant soft tissues: a review

Introduction: The implantological rehabilitation of the anterior sector is one of the most demanding and complex treatments due to the necessity of obtaining an optimum esthetic result. At the level of the soft tissues, it involves obtaining the complete formation of the papilla and creating a harmonic contour of the gingival margin.Objective: A bibliographical review has been carried out on the factors that influence the final position of the soft tissues.Material and methods: A search has been carried out in the Pubmed database of articles written in English and Spanish. Articles that presented a clinical series of less than five patients and a monitoring of less than one year were excluded.Results: At the level of the papilla, there are two decisive factors that play an influential role: the formation of the biological width and the distance between the alveolar crest and the contact point. The position of the gingival margin depends mainly of the height and width of the facial bone, as well as on the biotype. The surgical technique, as well as certain prosthodontics aspects related to the implant, can influence the final position of the soft tissues.Conclusions: Although, today we know much more about the factors that influence the position of the soft tissues, there are still certain aspects that should be studied more in-depth, for example the influence of the micro and macro-structure of the implant in the position of the soft tissues