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Search Results: 1 - 10 of 2869 matches for " Valente Ramirez "
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An example of a non-algebraizable singularity
Valente Ramirez
Mathematics , 2014,
Abstract: We say that the the germ of a singular holomorphic foliation on $(\mathbb{C}^2,0)$ is algebraizable whenever it is holomorphically conjugate to the singularity of a foliation defined globally on a projective algebraic surface. The object of this work is to construct a concrete example of a non--algebraizable singularity. Previously only existential results were known.
The utmost rigidity property for quadratic foliations on $\mathbb{P}^2$ with an invariant line
Valente Ramirez
Mathematics , 2014,
Abstract: In this work we consider holomorphic foliations of degree two on the projective plane $\mathbb{P}^2$ having an invariant line. In a suitable choice of affine coordinates these foliations are induced by a quadratic vector field over the affine part in such a way that the invariant line corresponds to the line at infinity. We say that two such foliations are topologically equivalent provided there exists a homeomorphism of $\mathbb{P}^2$ which brings the leaves of one foliation onto the leaves of the other and preserves orientation both on the ambient space and on the leaves. The main result of this paper is that in the generic case two such foliations may be topologically equivalent if and only if they are analytically equivalent. In fact, it is shown that the analytic conjugacy class of the holonomy group of the invariant line is the modulus of both topological and analytic classification. We obtain as a corollary that two generic orbitally topologically equivalent quadratic vector fields on $\mathbb{C}^2$ must be affine equivalent. This result improves, in the case of quadratic foliations, a well-known result by Ilyashenko that claims that two generic and topologically equivalent foliations with an invariant line at infinity are affine equivalent provided they are close enough in the space of foliations and the linking homeomorphism is close enough to the identity map on $\mathbb{P}^2$.
Twin vector fields and independence of spectra for quadratic vector fields
Valente Ramirez
Mathematics , 2015,
Abstract: The object of this paper is to address the following question: When is a polynomial vector field on $\mathbb{C}^2$ completely determined (up to affine equivalence) by the spectra of its singularities? We will see that for quadratic vector fields this is not the case: given a generic quadratic vector field there is, up to affine equivalence, exactly one other vector field which has the same spectra of singularities. Moreover, we will see that we can always assume that both vector fields have the same singular locus and at each singularity both vector fields have the same spectrum. Let us say that two vector fields are twin vector fields if they have the same singular locus and the same spectrum at each singularity. To formalize the above claim we shall prove the following: any two generic quadratic vector fields with the same spectra of singularities (yet possibly different singular locus) can be transformed by suitable affine maps to be either the same vector field or a pair of twin vector fields. We then analyze the case of quadratic Hamiltonian vector fields in more detail and find necessary and sufficient conditions for a collection of non-zero complex numbers to arise as the spectra of singularities of a quadratic Hamiltonian vector field. Lastly, we show that a generic quadratic vector field is completely determined (up to affine equivalence) by the spectra of its singularities together with the characteristic numbers of its singular points at infinity.
Embedding PV and WF Models into Steady State Studies by an Optimization Strategy  [PDF]
Juan Manuel Ramirez
Smart Grid and Renewable Energy (SGRE) , 2011, DOI: 10.4236/sgre.2011.23027
Abstract: Modeling of photovoltaic (PV) and wind farms (WF) stations to take into account these renewable energies into the power flow formulation are summarized. A strategy based on multi objective optimization in order to allocate PV and WF power into electrical power system is proposed. It is assumed that there are a reduced number of choices to allocate the stations. The algorithm is applied to the 39-bus test power system. The results show that the proposed algorithm is capable of optimal placement of renewable units.
Are Foreign and Public Investment Spending Productive in the Argentine Case? A Single Break Unit Root and Cointegration Analysis, 1960-2010.  [PDF]
Miguel D. Ramirez
Modern Economy (ME) , 2012, DOI: 10.4236/me.2012.36093
Abstract: This paper addresses the important question of whether public investment spending and inward foreign direct investment (FDI) flows enhance economic growth and labor productivity in Argentina. The paper estimates a dynamic labor productivity function for the 1960-2010 period that incorporates the impact of public and private investment spending, the labor force, and export growth. Single break (Zivot-Andrews) unit root and cointegration analysis suggest that (lagged) increases in public investment spending on economic and social infrastructure have a positive and significant effect on the rate of labor productivity growth. In addition, the model is estimated for a shorter period (1970-2010) to capture the impact of inward FDI flows. The estimates suggest that (lagged) inward FDI flows have a positive and significant impact on labor productivity growth, while increases in the labor force have a negative effect. From a policy standpoint, the findings call into question the politically expedient policy in many Latin American countries, including Argentina during the 1990s and early 2000s, of disproportionately reducing public capital expenditures to meet reducetions in the fiscal deficit as a proportion of GDP. The results give further support to progrowth policies designed to promote public investment spending and attract inward FDI flows.
Nurses' Psychosocial Barriers to Suicide Risk Management
Sharon Valente
Nursing Research and Practice , 2011, DOI: 10.1155/2011/650765
Abstract: Suicide remains a serious health care problem and a sentinel event tracked by The Joint Commission. Nurses are pivotal in evaluating risk and preventing suicide. Analysis of nurses' barriers to risk management may lead to interventions to improve management of suicidal patients. These data emerged from a random survey of 454 oncology nurses' attitudes, knowledge of suicide, and justifications for euthanasia. Instruments included a vignette of a suicidal patient and a suicide attitude questionnaire. Results. Psychological factors (emotions, unresolved grief, communication, and negative judgments about suicide) complicate the nurse's assessment and treatment of suicidal patients. Some nurses ( ) indicated that euthanasia was never justified and 11 were unsure of justifications and evaluated each case on its merits. Justifications for euthanasia included poor symptom control, poor quality of life, incurable illness or permanent disability, terminal illness, and terminal illness with inadequate symptom control or impending death, patient autonomy, and clinical organ death. The nurses indicated some confusion and misconceptions about definitions and examples of euthanasia, assisted suicide, and double effect. Strategies for interdisciplinary clinical intervention are suggested to identify and resolve these psychosocial barriers. 1. Psychosocial Barriers to Suicide Risk Management Patients facing a life-threatening illness such as cancer have an increased risk of suicide, and this study examines the nurse’s psychosocial barriers to managing suicide risk. Nurses have a major role to play in patient safety when they recognize the warning signs, monitor the patient’s emotional state, provide a therapeutic relationship, and take precautions to prevent suicide. Although 70% of people warn providers of their suicidal impulses, clinicians often fail to take these warnings seriously [1]. Therapeutic intervention can often effectively help alleviate the pain, symptoms, or depression and reduce suicide risk. Psychosocial barriers such as the nurse’s emotions, beliefs, knowledge, or attitudes can impair risk management. This paper describes content analysis of oncology nurses’ narratives about psychosocial barriers in managing suicide risk. People with cancer have higher than average rates of suicide. Rates of suicide have been estimated to be as high as 31.4/100,000 person-years among people with cancer or AIDS. [2]. Misono et al. found an age-, sex-, and race-adjusted rate of 31.4/100,000 person-years which is almost twice the general suicide rate in the US which was
Acolhimento familiar: validando e atribuindo sentido às leis protetivas
Valente, Jane;
Servi?o Social & Sociedade , 2012, DOI: 10.1590/S0101-66282012000300010
Abstract: in the context of the current brazilian legislation, which refers to children and adolescents in situations of vulnerability and risk, we will find a new service among the protective measures -provided: host service in welcoming family. given the unprecedented of this service as a public policy, this article aims to contribute to reflection about its execution in the country.
Indirizzi operativi per il trasferimento dei compiti catastali alle Amministrazioni locali
A. Valente
Aestimum , 1998,
Agnus Valente
ARS (S?o Paulo) , 2008, DOI: 10.1590/s1678-53202008000100024
The Orbit Space Approach to the Theory of Phase Transitions: The Non-Coregular Case
Gianpaolo Valente
Physics , 2000,
Abstract: We consider the problem of the determination of the isotropy classes of the orbit spaces of all the real linear groups, with three independent basic invariants satisfying only one independent relation. The results are obtained in the $\hat P$-matrix approach solving a universal differential equation ({\em master equation}) which involves as free parameters only the degrees $d_a$ of the invariants. We begin with some remarks which show how the $\hat{P}$-matrix approach may be relevant in physical contexts where the study of invariant functions is important, like in the analysis of phase spaces and structural phase transitions (Landau's theory).
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