1,971 research outputs found
Doubly Special Relativity with a minimum speed and the Uncertainty Principle
The present work aims to search for an implementation of a new symmetry in
the space-time by introducing the idea of an invariant minimum speed scale
(). Such a lowest limit , being unattainable by the particles, represents
a fundamental and preferred reference frame connected to a universal background
field (a vacuum energy) that breaks Lorentz symmetry. So there emerges a new
principle of symmetry in the space-time at the subatomic level for very low
energies close to the background frame (), providing a fundamental
understanding for the uncertainty principle, i.e., the uncertainty relations
should emerge from the space-time with an invariant minimum speed.Comment: 10 pages, 8 figures, Correlated paper in:
http://www.worldscientific.com/worldscinet/ijmpd?journalTabs=read. arXiv
admin note: substantial text overlap with arXiv:physics/0702095,
arXiv:0705.4315, arXiv:0709.1727, arXiv:0805.120
Lorentz violation with a universal minimum speed as foundation of de Sitter relativity
We aim to investigate the theory of Lorentz violation with an invariant
minimum speed so-called Symmetrical Special Relativity (SSR) from the viewpoint
of its metric. Thus we should explore the nature of SSR-metric in order to
understand the origin of the conformal factor that appears in the metric by
deforming Minkowski metric by means of an invariant minimum speed that breaks
down Lorentz symmetry. So we are able to realize that there is a similarity
between SSR and a new space with variable negative curvature () connected to a set of infinite cosmological constants
(), working like an extended de Sitter (dS) relativity, so
that such extended dS-relativity has curvature and cosmological "constant"
varying in the time. We obtain a scenario that is more similar to dS-relativity
given in the approximation of a slightly negative curvature for representing
the current universe having a tiny cosmological constant. Finally we show that
the invariant minimum speed provides the foundation for understanding the
kinematics origin of the extra dimension considered in dS-relativity in order
to represent the dS-length.Comment: 18 pages, 4 figures, correlated paper: arXiv:gr-qc/1308.5258 in
http://www.worldscientific.com/worldscinet/ijmpd?journalTabs=read , to be
presented in the Fifteenth Marcel Grossmann Meeting-MG15, University of Rome,
Italy, July 1-7, 2018: http://www.icra.it/mg/mg15
Variation of the speed of light with temperature of the expanding universe
From an extended relativistic dynamics for a particle moving in a cosmic
background field with temperature T, we aim to obtain the speed of light with
an explicit dependence on the background temperature of the universe. Although
finding the speed of light in the early universe much larger than its current
value, our approach does not violate the postulate of special relativity.
Moreover, it is shown that the high value of the speed of light in the early
universe was drastically decreased before the beginning of the inflationary
period. So we are led to conclude that the theory of varying speed of light
should be questioned as a possible solution of the horizon problem.Comment: 3 pages and 1 figure; Phys. Rev. D86, 027703 (2012
Quality of service control in IP networks using Fuzzy Logic for policy condition evaluation
This paper presents the architecture of a policy-
based network management system designed specifically for Quality of Service management, where high level business policies are modeled as ECA (Event-Condition-Action) rules. Specifically, the system is mainly based on the policy architecture being proposed by the IETF (Internet Engineering Task Force), DMTF (Distributed Management Task Force), and TMF (TeleManagement Forum) standardization bodies. This work proposes a novel approach for policy condition evaluation using
fuzzy logic. The fuzzy controller has the ability to examine policy conditions differently from default condition analyzers that employ simple conditions formed by a set of (IFs, ANDs and
ORs), allowing the consideration and correlation of several input variables before taking decisions for the execution of policy actions. The system have been implemented and evaluated over a test bed network formed by Cisco® routers
Predicting invasive breast cancer versus DCIS in different age groups.
BackgroundIncreasing focus on potentially unnecessary diagnosis and treatment of certain breast cancers prompted our investigation of whether clinical and mammographic features predictive of invasive breast cancer versus ductal carcinoma in situ (DCIS) differ by age.MethodsWe analyzed 1,475 malignant breast biopsies, 1,063 invasive and 412 DCIS, from 35,871 prospectively collected consecutive diagnostic mammograms interpreted at University of California, San Francisco between 1/6/1997 and 6/29/2007. We constructed three logistic regression models to predict the probability of invasive cancer versus DCIS for the following groups: women ≥ 65 (older group), women 50-64 (middle age group), and women < 50 (younger group). We identified significant predictors and measured the performance in all models using area under the receiver operating characteristic curve (AUC).ResultsThe models for older and the middle age groups performed significantly better than the model for younger group (AUC = 0.848 vs, 0.778; p = 0.049 and AUC = 0.851 vs, 0.778; p = 0.022, respectively). Palpability and principal mammographic finding were significant predictors in distinguishing invasive from DCIS in all age groups. Family history of breast cancer, mass shape and mass margins were significant positive predictors of invasive cancer in the older group whereas calcification distribution was a negative predictor of invasive cancer (i.e. predicted DCIS). In the middle age group--mass margins, and in the younger group--mass size were positive predictors of invasive cancer.ConclusionsClinical and mammographic finding features predict invasive breast cancer versus DCIS better in older women than younger women. Specific predictive variables differ based on age
Annexin/S100A protein family regulation through p14ARF-p53 activation: A role in cell survival and predicting treatment outcomes in breast cancer
© 2017 Hatoum et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. The annexin family and S100A associated proteins are important regulators of diverse calcium- dependent cellular processes including cell division, growth regulation and apoptosis. Dysfunction of individual annexin and S100A proteins is associated with cancer progression, metastasis and cancer drug resistance. This manuscript describes the novel finding of differential regulation of the annexin and S100A family of proteins by activation of p53 in breast cancer cells. Additionally, the observed differential regulation is found to be beneficial to the survival of breast cancer cells and to influence treatment efficacy. We have used unbiased, quantitative proteomics to determine the proteomic changes occurring post p14ARF-p53 activation in estrogen receptor (ER) breast cancer cells. In this report we identified differential regulation of the annexin/S100A family, through unique peptide recognition at the N-terminal regions, demonstrating p14ARF-p53 is a central orchestrator of the annexin/S100A family of calcium regulators in favor of pro-survival functions in the breast cancer cell. This regulation was found to be cell-type specific. Retrospective human breast cancer studies have demonstrated that tumors with functional wild type p53 (p53wt) respond poorly to some chemotherapy agents compared to tumors with a non-functional p53. Given that modulation of calcium signaling has been demonstrated to change sensitivity of chemotherapeutic agents to apoptotic signals, in principle, we explored the paradigm of how p53 modulation of calcium regulators in ER+ breast cancer patients impacts and influences therapeutic outcomes
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