252 research outputs found
Warping effects in strongly perturbed metrics
A technique devised some years ago permits to study a theory in a regime of
strong perturbations. This translates into a gradient expansion that, at the
leading order, can recover the BKL solution in general relativity. We solve
exactly the leading order Einstein equations in a spherical symmetric case,
assuming a Schwarzschild metric under the effect of a time-dependent
perturbation, and we show that the 4-velocity in such a case is multiplied by
an exponential warp factor when the perturbation is properly applied. This
factor is always greater than one. We will give a closed form solution of this
factor for a simple case. Some numerical examples are also given.Comment: 19 pages, 2 figures. Version accepted in Physic
The Role of Autologous Stem Cell Transplantation in the Treatment of Diffuse Large B-Cell Lymphoma
Diffuse large B-cell non-Hodgkin's lymphoma (DLBCL) accounting for approximately 30% of new lymphoma diagnoses in adult patients. Complete remissions (CRs) can be achieved in 45% to 55% of patients and cure in approximately 30–35% with anthracycline-containing combination chemotherapy. The ageadjusted IPI (aaIPI) has been widely employed, particularly to “tailor” more intensive therapy such as high-dose therapy (HDT) with autologous hemopoietic stem cell rescue (ASCT). IPI, however, has failed to reliably predict response to specific therapies. A subgroup of young patients with poor prognosis exists. To clarify the role of HDT/ASCT combined with rituximab in the front line therapy a longer follow-up and randomized studies are needed. The benefit of HDT/ASCT for refractory or relapsed DLBCL is restricted to patients with immunochemosensitive disease. Currently, clinical and biological research is focused to improve the curability of this setting of patients, mainly young
Uterine Sarcomas: An Updated Overview. Part 1: Smooth Muscle Tumors
Uterine sarcomas (USs) account for 3–9% of uterine malignant neoplasia and about 5% of all gynaecologic malignancies. Despite their low prevalence, these tumors stimulate a great interest because of their aggressiveness, poor prognosis and high mortality rate. According to the last World Health Organization (WHO) classification and the International Federation of Gynecology and Obstetrics Committee (FIGO) staging, USs are categorized as pure mesenchymal tumors (endometrial stromal sarcoma, leiomyosarcoma and undifferentiated uterine), and mixed tumors (carcinosarcoma and adenosarcoma). Due to their non-specific signs and symptoms, USs are commonly diagnosed in advanced stage, more often after surgery for a suspected leiomyoma. Although surgery followed by adjuvant therapies represent the common choices for USs, they show poor efficacy due to the early occurrence of metastasis, and the high resistance of tumors to radio-and chemotherapy. Presently, specific expression profiles and new cytotoxic agents are under investigation. In these reviews, we summarized clinical and pathological features, imaging characteristics, therapeutic approaches, genomic and molecular aberration associated with smooth muscle neoplasia (Part 1) and endometrial stromal neoplasia (Part 2); the goal is to understand the biology and the molecular signature of these tumors, in order to focus on their best management
Reproductive and pregnancy outcomes of fertility-sparing treatments for early-stage endometrial cancer or atypical hyperplasia: A systematic review and meta-analysis
To report the pregnancy outcomes of women with prior endometrial cancer and endometrial hyperplasia managed with fertility-sparing treatments
Clinical and genetic approach to the dysmorphic child
The child affected by a malformative syndrome represents a care challenge for the pediatrician. He is in fact the heart of the multidisciplinary team that has to manage the patient, trying to control the complications of his/her syndrome and promoting the correct psychophysical development. What we must not forget is that the pediatrician provides a continuous support to the child`s family, assisting them from the diagnosis to the management of problems related to the syndrome. This encourages the continuous follow-up of these children remembering also that the pediatrician is fundamental in the clinical management of the syndrome and for facilitating the social integration of these children
Ferromagnetism in tetragonally distorted LaCoO3 thin films
Thin films of epitaxial LaCoO{sub 3} were synthesized on SrTiO{sub 3} and (La, Sr)(Al, Ta)O{sub 3} substrates varying the oxygen background pressure in order to evaluate the impact of epitaxial growth as well as oxygen vacancies on the long range magnetic order. The epitaxial constraints from the substrate impose a tetragonal distortion compared to the bulk form. X-ray absorption and x-ray magnetic circular dichroism measurements confirmed that the ferromagnetism arises from the Co ions and persists through the entire thickness of the film. It was found that for the thin films to show ferromagnetic order they have to be grown under the higher oxygen pressures, since a decrease in oxygen deposition pressure alters the film structure and suppresses ferromagnetism in the LaCoO{sub 3} films. A correlation of the structure and magnetism suggests that the tetragonal distortions induce the ferromagnetism
On the entanglement entropy of quantum fields in causal sets
In order to understand the detailed mechanism by which a fundamental discreteness can provide a finite entanglement entropy, we consider the entanglement entropy of two classes of free massless scalar fields on causal sets that are well approximated by causal diamonds in Minkowski spacetime of dimensions 2,3 and 4. The first class is defined from discretised versions of the continuum retarded Green functions, while the second uses the causal set's retarded nonlocal d'Alembertians parametrised by a length scale lk. In both cases we provide numerical evidence that the area law is recovered when the double-cutoff prescription proposed in arXiv:hep-th/1611.10281 is imposed. We discuss in detail the need for this double cutoff by studying the effect of two cutoffs on the quantum field and, in particular, on the entanglement entropy, in isolation. In so doing, we get a novel interpretation for why these two cutoff are necessary, and the different roles they play in making the entanglement entropy on causal sets finite
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