12,381 research outputs found
Powerful Trend Function Tests That are Robust to Strong Serial Correlation with an Application to the Prebisch Singer Hypothesis
No full textIn this paper we propose tests for hypothesis regarding the parameters of a the deterministic trend function of a univariate time series. The tests do not require knowledge of the form of serial correlation in the data and they are robust to strong serial correlation. The data can contain a unit root and the tests still have the correct size asymptotically. The tests we analyze are standard heteroskedasticity autocorrelation (HAC) robust tests based on nonparametric kernel variance estimators. We analyze these tests using the small-b asymptotic framework recently proposed by Kiefer and Vogelsang (2002). This analysis allows us to analyze the power properties of the tests with regards to bandwidth and kernel choices. Our analysis shows that among popular kernels, there are specific kernel and bandwidth choices that deliver tests with maximal power within a specific class of tests. We apply the recommended tests to the logarithm of a net barter terms of trade series and we find that this series has a statistically significant negative slope. This finding is consistent with the well known Prebisch-Singer hypothesis. Because our tests are robust to strong serial correlation or a unit root in the data, our results in support of the Prebisch-Singer hypothesis are relatively strong.Estimator, Fixed-b Asymptotics, Power Envelope, Unit Root, Nearly Integrated, Partial Sum, Deterministic Trend, Linear Trend.
Deficits in high- (>60 Hz) gamma-band oscillations during visual processing in schizophrenia
No full textCurrent theories of the pathophysiology of schizophrenia have focused on abnormal temporal coordination of neural activity. Oscillations in the gamma-band range (>25 Hz) are of particular interest as they establish synchronization with great precision in local cortical networks. However, the contribution of high gamma (>60 Hz) oscillations toward the pathophysiology is less established. To address this issue, we recorded magnetoencephalographic (MEG) data from 16 medicated patients with chronic schizophrenia and 16 controls during the perception of Mooney faces. MEG data were analysed in the 25–150 Hz frequency range. Patients showed elevated reaction times and reduced detection rates during the perception of upright Mooney faces while responses to inverted stimuli were intact. Impaired processing of Mooney faces in schizophrenia patients was accompanied by a pronounced reduction in spectral power between 60–120 Hz (effect size: d = 1.26) which was correlated with disorganized symptoms (r = −0.72). Our findings demonstrate that deficits in high gamma-band oscillations as measured by MEG are a sensitive marker for aberrant cortical functioning in schizophrenia, suggesting an important aspect of the pathophysiology of the disorder
A importância moral da dor e do sofrimento animal na ética de Peter Singer
No full textDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências Humanas, Programa de Pós-Graduação em Filosofia, Florianópolis, 2012.O objetivo desta dissertação é defender a importância moral da consideração da dor e do sofrimento de animais não-humanos. Isso se dá através do principio da igual consideração de interesses desenvolvido por Peter Singer. A senciência possibilita os animais a terem interesses, no mínimo, o interesse evitar a dor e o sofrimento. É por essa razão que devem ser incluídos nas decisões morais. São reconstruídas e analisadas as objeções de Peter Harrison, Carl Cohen, R.G. Frey e Lawrence C. Becker direcionadas ao princípio de Singer, e que criticam os pressupostos básicos, quais sejam, a capacidade de sentirem dor/sofrimento e de terem interesses, sobre os quais se fundamenta a inclusão dos animais nas considerações morais. Cada uma dessas objeções é analisada e criticada de modo a demonstrar suas limitações e inconsistências, juntamente com as implicações morais geradas para seres humanos. Na análise dessas críticas, reforça-se a importância e a consideração moral que deve ser conferida à dor e ao sofrimento dos animais. Após essa discussão teórica, é analisado um caso de âmbito prático: a pesquisa científica sobre o câncer humano através do modelo animal. Verifica-se, a partir do princípio de Singer, a imoralidade de tal procedimento realizado em animais sencientes devido à violação de seus interesses. Com isso, a dissertação enfatiza a exigência ética de abolir o uso de animais nessa prática em razão da incapacidade preditiva dos animais, mas principalmente devido à dor e ao sofrimento causado neles e também aos seres humanos, que ficam sujeitos aos erros, prejuízos e sofrimentos originados pelo intenso uso animal nas pesquisas. Nessa conclusão, se constata que a insistência no uso de animais nos experimentos compromete o cientista a preferir usar seres humanos, uma vez que isso gera mais benefícios e resultados mais seguros. A recusa moral ao uso de humanos em pesquisas implica, por outro lado, na recusa moral do uso de animais, ou seja, sua abolição.Abstract : The aim of this dissertation is to defend the moral importance of considering pain and suffering of nonhuman animals. This is achieved through The Principle of Equal Consideration of Interests developed by Peter Singer. The sentience enables nonhuman animals to have interests, at least the interest of avoiding pain and suffering. That is why it should be included in moral decisions. The objections of Peter Harrison, Carl Cohen, RG Frey and Lawrence C. Becker directed to the principle of Singer are reconstructed and analyzed, as they are criticizing the basic assumptions, i.e., the ability to feel pain/suffering and have interests, upon which is based the inclusion of animals in moral considerations. Each of these objections is analyzed and criticized in order to demonstrate their limitations and inconsistencies, simultaneously with its moral implications for humans. In the analysis of these criticisms, it reinforces the moral importance and considerations that should be given to pain and suffering of animals. After this theoretical discussion, a case study of practical scope is analyzed: animal testing for scientific research on human cancer. It is verified from the Singer's principle that such procedures performed on sentient animals are a violation of their interests and, therefore, immoral. Thus, the dissertation emphasizes the ethical demand to abolish the use of nonhuman animals in this practice due to their predictive inability, but mainly due to the pain and suffering caused to them and also to humans, who are subject to errors, injuries and suffering originated by the intense use of nonhuman animals on research. The conclusion verifies that the insistence on the use of nonhuman animals in experiments moves the scientist to prefer using humans in experiments since it generates greater benefit and more reliable results. The moral refusal to using humans in research implies the moral rejection of the use of animals in experiments and consequently, its abolition
Can reforming global institutions help developing countries share more in the benefits from globalization?
No full textGlobalization could significantly expand trade, international investment, and technological advances, but the gains from global integration have been unevenly distributed across and within nations. Greater global interdependence has also brought greater macroeconomic volatility, resulting in several serious financial crises in the second half of the 1990s. The global matrix of Bretton Woods and United Nations institutions that developed starting in the 1940s, formed under a different balance of power, in a world of fixed exchange rates and limited capital mobility. Since the 1960s regional financial institutions have emerged because of the greater autonomy of different regions and the greater financial needs of development. The author reviews different proposals for reform of the international financial institutions and changes in the roles of the International Monetary Fund (IMF) and the World Bank. He highlights the implications for developing countries of (1) Policy conditionality. (2) The countercyclical role of multilaterals'lending. (3) Greater lending to middle-income than to low-income developing countries. (3) Access to liquidity at times of crisis. (4) Mechanisms for giving low-income countries a greater voice in IMF and World Bank decisionmaking. The author streses the overlapping responsibilities of the Bretton Woods and regional financial institutions and the need to reassess the allocation of responsibilities and to develop better coordination mechanisms between these institutions. Those designing institutional reform must consider the corporate capabilities of each type of institution. The corporate cultures of global and regional institutions differ. So does the kind of knowledge they generate and disseminate, and so do patterns of interactions with, and mechanisms for representation of, client countries.Finally, the author calls attention to the need to harmonize national and global growth-oriented policies in a way that reduces volatility and promotes social equity.Environmental Economics&Policies,Governance Indicators,Financial Intermediation,Economic Theory&Research,Banks&Banking Reform
Assessment of cardiac output, intravascular volume status, and extravascular lung water by transpulmonary indicator dilution in critically ill neonates and infants
No full textObjective: To assess cardiac output, intrathoracic blood volume, global end-diastolic volume, and extravascular lung water in critically ill neonates and small infants using transpulmonary indicator dilution. Design: Prospective, observational, clinical study. Setting: Pediatric intensive care unit in a university hospital. Participants: Critically ill neonates and small infants suffering from severe heart failure, respiratory failure, or sepsis (n = 10). Interventions: A total of 194 transpulmonary indicator dilution measurements were done. Global end-diastolic volume, intrathoracic blood volume, and stroke volume were measured and compared with standard hemodynamic parameters during the clinical course and before and after volume loading (16.+/- 3.7 mL/kg of 10% albumin solution) in 8 of 10 patients. Measurements and Main Results: A positive correlation was found for stroke volume index versus global end-diastolic volume (r = 0.76, p < 0.001) and intrathoracic blood volume (r = 0.56, p < 0.001). In contrast, no correlation was observed for stroke volume index versus central venous pressure. Volume loading resulted in significant increases in stroke volume index (p < 0.01), global end-diastolic volume (p < 0.01), and intrathoracic blood volume (p < 0.01); whereas central venous pressure, heart rate, mean arterial pressure, and extravascular lung water remained unchanged. Conclusion: Transpulmonary indicator dilution enables measurement of cardiac output and intravascular volume status in critically ill neonates and infants at the bedside. The effects of volume loading on cardiac preload and effective change in stroke volume can be monitored by this technique, whereas central venous pressure was not indicative of changes in intravascular volume status. Copyright 2002, Elsevier Science (USA). All rights reserved
Valor intrínseco na bioética ambiental: uma análise crítica das concepções de Dworkin, Singer e Rolston III
No full textDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Filosofia e Ciências Humanas, Programa de Pós-Graduação em Filosofia, Florianópolis, 2010O tema desta dissertação é o valor intrínseco e sua aplicabilidade no contexto da bioética ambiental. Discute-se, sobretudo, as concepções de valor intrínseco apresentadas por Ronald Dworkin, Peter Singer e Holmes Rolston III. Tais autores possuem concepções de valor intrínseco diversas e delas realizam diferentes usos e aplicações, o que origina o problema desta pesquisa, levando-nos a questionar se tais concepções de valor intrínseco realmente são suficientes para se propor uma teoria bioética ambiental. A hipótese considerada é a de que dependendo do conceito e do uso da expressão "valor intrínseco", a concepção adotada pelos filósofos não é suficientemente adequada para fundamentar ou, pelo menos, apoiar a construção de uma proposta de ética ambiental que garanta individualmente igual proteção às mais diversas formas de vida. Assim, o objetivo consiste em analisar diversos usos e aplicações de concepções de valor intrínseco na ética prática e, mais especificamente, verificar os limites dessas concepções na sua aplicação no contexto de teorias bioéticas. A partir disso, aponta-se para uma concepção de "valor inerente" para a qual uma ética ambiental genuína deve voltar-se, sem descartar as contribuições de Dworkin, Singer e Rolston III. Para tanto, defende-se a importância de superar uma visão representacionista de mundo, segundo a qual os seres humanos são concebidos enquanto entidades separadas do restante do mundo natural, substituindo-a por uma concepção de natureza que entende os seres humanos como parte do mundo natural, que, por sua vez, é continuamente construído pela interação mente e mundo
Distributed processing and temporal codes in neuronal networks
No full textThe cerebral cortex presents itself as a distributed dynamical system with the characteristics of a small world network. The neuronal correlates of cognitive and executive processes often appear to consist of the coordinated activity of large assemblies of widely distributed neurons. These features require mechanisms for the selective routing of signals across densely interconnected networks, the flexible and context dependent binding of neuronal groups into functionally coherent assemblies and the task and attention dependent integration of subsystems. In order to implement these mechanisms, it is proposed that neuronal responses should convey two orthogonal messages in parallel. They should indicate (1) the presence of the feature to which they are tuned and (2) with which other neurons (specific target cells or members of a coherent assembly) they are communicating. The first message is encoded in the discharge frequency of the neurons (rate code) and it is proposed that the second message is contained in the precise timing relationships between individual spikes of distributed neurons (temporal code). It is further proposed that these precise timing relations are established either by the timing of external events (stimulus locking) or by internal timing mechanisms. The latter are assumed to consist of an oscillatory modulation of neuronal responses in different frequency bands that cover a broad frequency range from 40 Hz (gamma) and ripples. These oscillations limit the communication of cells to short temporal windows whereby the duration of these windows decreases with oscillation frequency. Thus, by varying the phase relationship between oscillating groups, networks of functionally cooperating neurons can be flexibly configurated within hard wired networks. Moreover, by synchronizing the spikes emitted by neuronal populations, the saliency of their responses can be enhanced due to the coincidence sensitivity of receiving neurons in very much the same way as can be achieved by increasing the discharge rate. Experimental evidence will be reviewed in support of the coexistence of rate and temporal codes. Evidence will also be provided that disturbances of temporal coding mechanisms are likely to be one of the pathophysiological mechanisms in schizophrenia
Topographic relations between ocular dominance and orientation columns in the cat striate cortex
No full textLöwel S, Bischof H-J, Leutenecker B, Singer W. Topographic relations between ocular dominance and orientation columns in the cat striate cortex. Experimental Brain Research. 1988;71(1):33-46.In the visual cortex of four adult cats ocular dominance and orientation columns were visualized with (3H)proline and (14C)deoxyglucose autoradiography. The two columnar systems were reconstructed from serial horizontal sections or from flat-mount preparations and graphically superimposed. They share a number of characteristic features: In both systems the columns have a tendency to form regularly spaced parallel bands whose main trajectory is perpendicular to the border between areas 17 and 18. These bands frequently bifurcate or terminate in blind endings. The resulting irregularities are much more pronounced in the ocular dominance than in the orientation system. The periodicity of the columnar patterns was assessed along trajectories perpendicular to the main orientation of the bands and differed in the two columnar systems. The spacing of the ocular dominance stripes was significantly narrower than the spacing of orientation bands. The mean periodicity of a particular columnar system was virtually identical in the two hemispheres of the same animal but it differed substantially in different animals. However, the spacing of orientation columns covaried with that of the ocular dominance columns, the ratios of the mean spacings of the two columnar systems being similar in the four cats. The superposition of the two columnar systems revealed no obvious topographic relation between any of the organizational details such as the location of bifurcations, blind endings and intersections. We suggest the following conclusions: 1. The developmental processes generating the two columnar systems seem to obey the same algorithms but they act independently of each other. 2. The space constants of the two systems are rigorously specified and appear to depend on a common variable. 3. The main orientation of the bands in both columnar systems is related to a) the representation of the vertical meridian, b) the anisotropy of the cortical magnification factor, and c) the tangential spread of intracortical connections
The Prebisch-Singer Hypothesis: A Reappraisal Independent of Stationarity Hypotheses.
No full textStructural time series analysis, which requires no prior assumptions regarding stationarity and allows for a wide variety of behavior, reveals that the net barter terms of trade between primary commodities and manufactures has a negative deterministic trend over this century as hypothesized by R. Prebisch (1950) and H. Singer (1950). However, the rate of decline is only about half what is predicted using the data available to Prebisch and Singer. The authors' finding of secular deterioration is robust; it holds if data after the oil shock of 1973, or before a previously claimed structural shift in 1921, are excluded from the sample. Copyright 1992 by Royal Economic Society.
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