Some results on anisotropic mean curvature and other phase transition models

The present thesis is divided into three parts. In the first part, we analyze a suitable regularization \u2014 which we call nonlinear multidomain model \u2014 of the motion of a hypersurface under smooth anisotropic mean curvature flow. The second part of the thesis deals with crystalline mean curvature of facets of a solid set of R^3 . Finally, in the third part we study a phase-transition model for Plateau\u2019s type problems based on the theory of coverings and of BV functions

Optical absorption modulation by selective codoping of SiGe core-shell nanowires

n/

Interplay of Quantum Confinement and Strain Effects in Type I to Type II Transition in GeSi Core-Shell Nanocrystals

The electronic properties of hydrogenated, spherical SiGe and GeSi core-shell nanocrystals, with a diameter ranging from 1.8 to 4.0 nm, are studied within density functional theory. Effects induced by quantum confinement and strain on the near band-edge state localization, as well as the band-offset properties between Si and Ge regions, are investigated in detail. On the one hand, we prove that SiGe core-shell nanocrystals always show a type II band-offset alignment, with the HOMO mainly localized on the Ge shell region and the LUMO mainly localized on the Si core region. On the other hand, our results point out that a type II offset cannot be observed in small (diameter less than 3 nm) GeSi core- shell nanocrystals. In these systems, quantum confinement and strain drive the near-band-edge states to be mainly localized on Ge atoms, i.e., in the core region. In larger GeSi core-shell nanocrystals, instead, the formation of a type II offset can be engineered by playing with both core and shell thickness. The factors which determine the band-offset character at the Ge/Si interface are discussed in detail

Application of Graph Theory to the elaboration of personal genomic data for genealogical research

In this communication a representation of the links between DNA-relatives based on Graph Theory is applied to the analysis of personal genomic data to obtain genealogical information. The method is tested on both simulated and real data and its applicability to the field of genealogical research is discussed. We envisage the proposed approach as a valid tool for a streamlined application to the publicly available data generated by many online personal genomic companies. In this way, anonymized matrices of pairwise genome sharing counts can help to improve the retrieval of genetic relationships between customers who provide explicit consent to the treatment of their data

TEM in the treatment of recurrent rectal cancer in elderly

INTRODUCTION: Transanal microscopic surgery is an important application of minimally invasive surgery of rectum, allowing realization of complex transanal intervention. PATIENTS AND METHODS: During the period between January 2002 and December 2010, seven patients, five men and two women, average age 75 years, with early rectal cancer recurrence were selected for this type of surgical palliative procedure. The selection of the patients is made by: transrectal ultrasonografy, colonoscopy and abdominal ultrasonografy, to rule out liver metastases, CT with and without enema, PET CT. Follow-up is approximately 12-30 months. RESULTS: The pathologic staging confirms the complete excision of recurrences. Then patients are referred for more complementary therapies. DISCUSSION: The significance of conservative treatment for local recurrence of rectum adenocarcinoma is still controversial because the recurrence is an expression of tumor spread not controlled by oncological surgical and radio/chemo therapy. CONCLUSION: In selected subjects such as the elderly, based on equal oncological treatment, the reduction of surgical trauma, preservation of anatomical integrity and resolution of symptoms are important results

Surgical mistake causing an high recto-vaginal fistula. A case report with combined surgical and endoscopic approach: therapeutic considerations

BACKGROUND: Rectovaginal fistulas (RVFs) have multiple causes, size and location on which the surgical treatment depends. DESCRIPTION: The Authors consider different approaches to RVFs and describe a clinical case of recurrent high RVF. CONCLUSIONS: Most RVFs can be successfully repaired, although many interventions may be necessary. A colostomy with delayed repair may improve RVFs outcome. Moreover, several authors indicate Mucosal Advancement Flap and Babcock-Bacon technique as the treatments of choice respectively for low and high RVFs (complex and recurrent) and emphasize the placement of endoscopic prothesis in cases of difficult healing of the anastomosis