927 research outputs found
Geometric Quantization on the Super-Disc
In this article we discuss the geometric quantization on a certain type of
infinite dimensional super-disc. Such systems are quite natural when we analyze
coupled bosons and fermions. The large-N limit of a system like that
corresponds to a certain super-homogeneous space. First, we define an example
of a super-homogeneous manifold: a super-disc. We show that it has a natural
symplectic form, it can be used to introduce classical dynamics once a
Hamiltonian is chosen. Existence of moment maps provide a Poisson realization
of the underlying symmetry super-group. These are the natural operators to
quantize via methods of geometric quantization, and we show that this can be
done.Comment: 17 pages, Latex file. Subject: Mathematical physics, geometric
quantizatio
The Current Perspectives of Stem Cell Therapy in Orthopedic Surgery
Context: Musculoskeletal injuries may be painful, troublesome, life limiting and also one of the global health problems. There has been considerable amount of interest during the past two decades to stem cells and tissue engineering techniques in orthopedic surgery, especially to manage special and compulsive injuries within the musculoskeletal system.
Evidence Acquisition: The aim of this study was to present a literature review regarding the most recent progress in stem cell procedures and current indications in orthopedics clinical care practice. The Medline and PubMed library databases were searched for the articles related with stem cell procedures in the field of orthopedic surgery and additionally the reference list of each article was also included to provide a comprehensive evaluation.
Results: Various sources of stem cells have been studied for orthopedics clinical care practice. Stem cell therapy has successfully used for major orthopedic procedures in terms of bone-joint injuries (fractures-bone defects, nonunion, and spinal injuries), osteoarthritis-cartilage defects, ligament-tendon injuries, femoral head osteonecrosis and osteogenesis imperfecta. Stem cells have also used in bone tissue engineering in combining with the scaffolds and provided faster and better healing of tissues.
Conclusions: Large amounts of preclinical studies have been made of stem cells and there is an increasing interest to perform these studies within the human population but preclinical studies are insufficient; therefore, much more and efficient studies should be conducted to evaluate the efficacy and safety of stem cells
Finitely Many Dirac-Delta Interactions on Riemannian Manifolds
This work is intended as an attempt to study the non-perturbative
renormalization of bound state problem of finitely many Dirac-delta
interactions on Riemannian manifolds, S^2, H^2 and H^3. We formulate the
problem in terms of a finite dimensional matrix, called the characteristic
matrix. The bound state energies can be found from the characteristic equation.
The characteristic matrix can be found after a regularization and
renormalization by using a sharp cut-off in the eigenvalue spectrum of the
Laplacian, as it is done in the flat space, or using the heat kernel method.
These two approaches are equivalent in the case of compact manifolds. The heat
kernel method has a general advantage to find lower bounds on the spectrum even
for compact manifolds as shown in the case of S^2. The heat kernels for H^2 and
H^3 are known explicitly, thus we can calculate the characteristic matrix.
Using the result, we give lower bound estimates of the discrete spectrum.Comment: To be published in JM
INVESTIGATION OF ALTERNATIVE TOURISM TYPES AND SIGHTS VIA GEOGRAPHIC INFORMATION SYSTEMS: THE EXAPLE OF SAFRANBOLU
Point Interaction in two and three dimensional Riemannian Manifolds
We present a non-perturbative renormalization of the bound state problem of n
bosons interacting with finitely many Dirac delta interactions on two and three
dimensional Riemannian manifolds using the heat kernel. We formulate the
problem in terms of a new operator called the principal or characteristic
operator. In order to investigate the problem in more detail, we then restrict
the problem to one particle sector. The lower bound of the ground state energy
is found for general class of manifolds, e.g., for compact and Cartan-Hadamard
manifolds. The estimate of the bound state energies in the tunneling regime is
calculated by perturbation theory. Non-degeneracy and uniqueness of the ground
state is proven by Perron-Frobenius theorem. Moreover, the pointwise bounds on
the wave function is given and all these results are consistent with the one
given in standard quantum mechanics. Renormalization procedure does not lead to
any radical change in these cases. Finally, renormalization group equations are
derived and the beta-function is exactly calculated. This work is a natural
continuation of our previous work based on a novel approach to the
renormalization of point interactions, developed by S. G. Rajeev.Comment: 43 page
Reconstruction of Coracoclavicular Ligaments with Semitendinosus Autograft and Temporary Kirschner Wires is a good option for Chronic Acromioclavicular Joint Instability
Introduction: This study reports the results of surgical anatomic reconstruction of torn coracoclavicular ligaments with an autogenous semitendinosus graft and temporary Kirschner wires (K-wires) in chronic acromioclavicular (AC) joint dislocations.
Materials and methods: Nineteen shoulders underwent surgical anatomic reconstruction of torn coracoclavicular (CC)ligaments with an autogenous semitendinosus tendon graft and temporary K-wires for Rockwood grade III, IV and V chronic AC joint dislocations. Pre-operative data included patients’ demographic characteristics, injury characteristics and surgical histories. The primary outcome measures were the University of California Los Angeles (UCLA) shoulder rating scale and visual analogue pain scoring (VAS), and the complications were noted for each patient.
Results: Surgical anatomic reconstruction of torn CC ligaments was performed in 19 patients with a mean age of41.6±16 years (range 21–72 years). All of the patients were satisfied and felt better after CC ligament reconstruction. The average UCLA shoulder rating scale score was good/excellent: 29.4 (range 23–34) out of 35 points. The average pre-operative VAS score was 7.7 points out of 10and improved to 1.1 points post-operatively (p<0.05). None of the patients experienced failure during the follow-up. One patient had a mild subluxation, but the patient was satisfied with the result.
Conclusions: This technique is simple, reliable, and biologic without major complications. It is also a cost-effective procedure since it can be performed with Kirschner wire sand autogenous grafts. It has a major advantage of leaving no implants inside the joint, which can lead to hardware complications, and it can be performed in basic operating room settings
A Many-body Problem with Point Interactions on Two Dimensional Manifolds
A non-perturbative renormalization of a many-body problem, where
non-relativistic bosons living on a two dimensional Riemannian manifold
interact with each other via the two-body Dirac delta potential, is given by
the help of the heat kernel defined on the manifold. After this renormalization
procedure, the resolvent becomes a well-defined operator expressed in terms of
an operator (called principal operator) which includes all the information
about the spectrum. Then, the ground state energy is found in the mean field
approximation and we prove that it grows exponentially with the number of
bosons. The renormalization group equation (or Callan-Symanzik equation) for
the principal operator of the model is derived and the function is
exactly calculated for the general case, which includes all particle numbers.Comment: 28 pages; typos are corrected, three figures are adde
Diagnostic value of combined serum biomarkers for the evaluation of liver fibrosis in chronic hepatitis C infection: A multicenter, noninterventional, observational study
Background/Aims: The hepatitis C virus (HCV) infection is important cause of chronic hepatitis. Liver biopsy is considered the gold standard for assessment of fibrosis but this procedure is an invasive procedure. We aimed to evaluate the diagnostic efficiency of non-invasive serum biomarkers, separately and in combinations, on liver fibrosis in treatment-naive chronic hepatitis C (CHC) patients. Materials and Methods: Two hundred and sixteen treatment-naive CHC patients were enrolled from 32 locations across Turkey in this open-labelled, non-interventional prospective observational study. FibroTest®, aspartate aminotransferase-to-platelet ratio index(APRI), aspartate aminotransferase and alanine aminotransferase ratio (AAR), fibrosis index based on four factors (FIB-4), Age-platelet(AP) index and Forns index were measured and compared with Metavir scores got from liver biopsies. Results: Data from 182 patients with baseline liver biopsy were suitable for analysis. One hundred and twenty patients (65.9%) had F0-F1 fibrosis and 62 patients (34.1%) had F2-F4 fibrosis. APRI 0.732 area under the curve(AUC) indicated advanced fibrosis with 69% sensitivity and 77% specificity. FIB-4 0.732 AUC and FibroTest 0.715 AUC indicated advanced fibrosis with 69% and 78.4% sensitivity, and 75% and 71.4% specificity, respectively. The combined use of tests also led to an increase in AUC and specificity. Combinations of FibroTest with APRI and/or FIB-4, and FIB-4 with APRI were optimal for the evaluation of liver fibrosis. Conclusion: Fibrotest, FIB-4, APRI, AP index and Forns index exhibit good diagnostic performance for determining liver fibrosis in CHC patients, and the use of at least two tests together will increase their diagnostic value still further. © Copyright 2018 by The Turkish Society of Gastroenterology
Carotid Artery Stenting: A Single Center “Real World” Experience
BACKGROUND:Percutaneous carotid artery stenting (CAS) became a widely used procedure in patients with symptomatic and asymptomatic carotid artery stenosis. However its role compared to carotid endarterectomy (CAD) remains questioned. We analysed the safety of carotid artery stenting program of a prospective CAS register program of a tertiary teaching hospital.
METHOD:Between July 2003 and December 2010, 208 patients underwent CAS procedure. Baseline, procedural and follow-up data were prospectively collected. Primary peri-interventional outcome was defined as 30-day major adverse events (MAE), including death, stroke or myocardial infarction, and mid- to long-term follow-up outcome included ipsilateral stroke, myocardial infarction or death. Secondary outcome was restenosis rate ≥ 50% per lesion.
RESULTS:Unilateral carotid artery interventions were performed in 186 patients. In 22 patients CAS was performed bilaterally as stages procedures. The 30-day MAE rate was 1.9% consisting of two contralateral strokes and two ipsilateral stroke. Mean clinically follow-up was 22 months. Mid- to long-term MAE was 8.1% with 6.3% (n = 13) deaths, 1.9% (n = 4) myocardial infarctions and 0.9% (n = 2) ipsilateral stroke. The restenosis rate ≥ 50% per lesion was 4.3% at a mean follow-up of 22 months. Target lesion revascularization was performed in one patient, because of restenosis at 9 months follow-up after first CAS.
CONCLUSION:Implementation of a carotid artery stenting program at a tertiary, teaching hospital is a safe method for treatment of carotid artery stenosis. The adverse event rate during mid-to-long-term follow-up suggests an appropriate patient selection
- …