Conformal fields in the pp-wave limit

The pp-wave (Penrose limit) in conformal field theory can be viewed as a special contraction of the unitary representations of the conformal group. We study the kinematics of conformal fields in this limit in a geometric approach where the effect of the contraction can be visualized as an expansion of space-time. We discuss the two common models of space-time as carrier spaces for conformal fields: One is the usual Minkowski space and the other is the coset of the conformal group over its maximal compact subgroup. We show that only the latter manifold and the corresponding conformal representation theory admit a non-singular contraction limit. We also address the issue of correlation functions of conformal fields in the pp-wave limit. We show that they have a well-defined contraction limit if their space-time dependence merges with the dependence on the coordinates of the R symmetry group. This is a manifestation of the fact that in the limit the space-time and R symmetries become indistinguishable. Our results might find applications in actual calculations of correlation functions of composite operators in N=4 super Yang-Mills theory.Comment: LaTex, 32 pages, 1 figure, discussion of correlation functions extended; some corrections made; references adde

Quantum Groups, Gravity, and the Generalized Uncertainty Principle

We investigate the relationship between the generalized uncertainty principle in quantum gravity and the quantum deformation of the Poincar\'e algebra. We find that a deformed Newton-Wigner position operator and the generators of spatial translations and rotations of the deformed Poincar\'e algebra obey a deformed Heisenberg algebra from which the generalized uncertainty principle follows. The result indicates that in the $\kappa$-deformed Poincar\'e algebra a minimal observable length emerges naturally.Comment: 13 pages, IFUP-TH 19/93, May 1993 (revised Nov. 1993

Quantum Mechanics from Focusing and Symmetry

A foundation of quantum mechanics based on the concepts of focusing and symmetry is proposed. Focusing is connected to c-variables - inaccessible conceptually derived variables; several examples of such variables are given. The focus is then on a maximal accessible parameter, a function of the common c-variable. Symmetry is introduced via a group acting on the c-variable. From this, the Hilbert space is constructed and state vectors and operators are given a clear interpretation. The Born formula is proved from weak assumptions, and from this the usual rules of quantum mechanics are derived. Several paradoxes and other issues of quantum theory are discussed.Comment: 26 page

The importance of examining antinuclear antibody (ANA) in neurological diseases [Nörolojik hastaliklarda antinükleer antikor (ana) incelemesinin önemi]

Objective: In neurological clinical practice screening test for ANA (Anti-nuclear antibody) is helpful in the diagnosis of autoimmune diseases which have neurological involvement. ANA investigation tests might be positive both in connective tissue disorders with neurological symptoms, such as Systemic Lupus Erythematosus, Sjogren's disease, Rheumatoid Arthritis and also in neurological diseases in the which autoimmune system is responsible such as Multiple Sclerosis (MS) and Myastenia Gravis. In addition drug usage and older age are the factors which might cause positive results in ANA screening tests. In this study we aimed to investigate the neurological diseases which are associated with postive ANA tests and to understand the efficiency of this screening test in neurological practice. Material and Method: The patients who were followed up in neurology outpatient clinic with positive ANA test were investigated. The medical records of 309 patients with positive ANA results were evaluated. The most common neurological diseases with positive ANA and ANA patterns were determined. Results: The patients who were thought to be demyelinating disease had the highest number of positive ANA results. However, positive ANA results were also found with different and non specific neurological symptoms. Conclusion: As a result of the diagnosis of neurological diseases, positive ANA results might be beneficial in patients with supportive medical history and laboratory findings

Nörolojik hastaliklarda antinükleer antikor (ana) incelemesinin önemi]

Objective: In neurological clinical practice screening test for ANA (Anti-nuclear antibody) is helpful in the diagnosis of autoimmune diseases which have neurological involvement. ANA investigation tests might be positive both in connective tissue disorders with neurological symptoms, such as Systemic Lupus Erythematosus, Sjogren's disease, Rheumatoid Arthritis and also in neurological diseases in the which autoimmune system is responsible such as Multiple Sclerosis (MS) and Myastenia Gravis. In addition drug usage and older age are the factors which might cause positive results in ANA screening tests. In this study we aimed to investigate the neurological diseases which are associated with postive ANA tests and to understand the efficiency of this screening test in neurological practice. Material and Method: The patients who were followed up in neurology outpatient clinic with positive ANA test were investigated. The medical records of 309 patients with positive ANA results were evaluated. The most common neurological diseases with positive ANA and ANA patterns were determined. Results: The patients who were thought to be demyelinating disease had the highest number of positive ANA results. However, positive ANA results were also found with different and non specific neurological symptoms. Conclusion: As a result of the diagnosis of neurological diseases, positive ANA results might be beneficial in patients with supportive medical history and laboratory findings

Relationship of cognitive functions with daily living activities, depression, anxiety and clinical variables in hospitalized elderly patients [Hastanede yatan yaşlılarda bilişsel İşlevlerin günlük yaşam aktiviteleri, depresyon, anksiyete ve klinik değişkenlerle İlişkisi]

Introduction: Cognitive impairment in elderly patients, which may be a sign of dementia, depression, anxiety or medical diseases, has been determined as a risk factor for functional loss. In this study, we aimed to investigate the frequency of cognitive impairment and to investigate the relationship of cognitive status with sociodemographic variables, daily living activities, anxiety and depression in elderly inpatients.Method: The sample of this cross-sectional and descriptive study consists of 243 patients aged 65 years and older who were hospitalized in Bülent Ecevit University Hospital. A sociodemographic questionnaire, the Mini-Mental State Examination (MMSE), Activities of Daily Living Scale, Lawton-Brody Instrumental Daily Activities Scale, Geriatric Depression Scale (GDS) and the Beck Anxiety Inventory were used for data collection.Results: One hundred and six (43.6%) patients were female and 137 (56.4%) were male. The patients were divided into two groups according to the Mini-Mental State Examination (MMSE) 23/24 cut-off score. The cognitive decline was statistically significantly more frequent in patients who were older, female, less educated, low socioeconomic status, and living in rural areas. There were more problems in the basic and instrumental activities of daily living and nutrition in patients with cognitive decline. Anxiety and depression scores were higher in this group. In our study, although the frequency of cognitive decline and depression according to GDS were 56% and 48%, respectively; we found that only 10.5% of patients applied to the psychiatrist, and 9.3% of patients received psychiatric treatment.Conclusion: Cognitive decline may cause deterioration in the daily living activities, nutrition and capacity for independent functioning. Older age, female, low education, low socioeconomic status and living in rural area are important risk factors for cognitive impairment. Cognitive decline in older age may be associated with depression and anxiety. We assume that when cognitive decline, depression and other psychiatric problems are unidentified, it may contribute to deterioration of mental health in medically ill elderly. © 2014 Galenos Yayinevi. All rights reserved