A tenseless account of tensed sentences and tensed belief.

In this dissertation I provide a tenseless account of tensed sentences and tensed belief. I begin by distinguishing tensed theories of time from tenseless theories of time. Tensed theories of time hold (a) that there is a time that is objectively present, and (b) that the moment that is objectively present changes from one moment to the next. I reject tensed theories of time. I deny that there is a time that is objectively present that changes from one moment to the next. Instead, time is in many ways analogous to space and \u27now\u27 is in many ways analogous to \u27here\u27. Just as there is no one location that is objectively here, there is no one moment that is objectively now. Nothing metaphysically distinguishes the present moment from past and future moments. There are two major challenges facing the tenseless theory of time. The first challenge is: can a tenseless theory of time provide a plausible account of the truth-conditions for tensed sentences? Tensed sentences such as \u27The meeting is now!\u27 provide a prima facie reason in favor of irreducibly tensed properties: the sentence is true if and only if the meeting has the tensed property of being now. I examine existing attempts by tenseless theorists for providing tenseless truth-conditions for tensed sentences. I argue that they are unable to provide a complete account of what makes tensed sentences true. I formulate and defend a new tenseless account of the truth-conditions for tensed sentences, the type-context theory, which makes use of David Kaplan\u27s theory of indexicals. The second challenge facing the tenseless theory of time is: can a tenseless theory of time provide a plausible account of our tensed psychological attitudes? Most of our psychological attitudes such as belief, desire, relief, regret and anticipation are irreducibly tensed: we cannot adequate describe such attitudes without appealing to tensed language. I do not take relief in the tenseless fact that I got my wisdom teeth out in 1998. I take relief in the tensed fact that my wisdom teeth were extracted in the past. I do not run to the bus stop merely because I believe that the bus arrives at 8:45. I run to the bus stop because I believe that the bus is arriving now. How can the tenseless theory of time explain the central role that tense plays in our psychological attitudes? I claim that the objects of tensed beliefs are properties (or relations). The account I defend is a version of the self-ascription accounts defended by Roderick Chisholm and David Lewis. I argue that such a view can provide a plausible tenseless account of tensed belief

Manipulation of single-photon states encoded in transverse spatial modes: possible and impossible tasks

Controlled generation and manipulation of photon states encoded in their spatial degrees of freedom is a crucial ingredient in many quantum information tasks exploiting higher-than-two dimensional encoding. Here, we prove the impossibility to arbitrarily modify $d$-level state superpositions (qu$d$its) for $d>2$, encoded in the transverse modes of light, with optical components associated to the group of symplectic transforms (Gaussian operations). Surprisingly, we also provide an explicit construction of how non-Gaussian operations acting on mode subspaces do enable to overcome the limit $d=2$. In addition, this set of operations realizes the full SU(3) algebra.Comment: Published in PR

Differential Operators for Edge Detection

We present several results characterizing two differential operators used for edge detection: the Laplacian and the second directional derivative along the gradient. In particular, (a)we give conditions for coincidence of the zeros of the two operators, and (b) we show that the second derivative along the gradient has the same zeros of the normal curvature in the gradient direction. Biological implications are also discussed. An experiment is suggested to test which of the two operators may be used by the human visual system.MIT Artificial Intelligence Laborator

EPR before EPR: a 1930 Einstein-Bohr thought experiment revisited

In 1930 Einstein argued against consistency of the time-energy uncertainty relation by discussing a thought experiment involving a measurement of mass of the box which emitted a photon. Bohr seemingly triumphed over Einstein by arguing that the Einstein's own general theory of relativity saves the consistency of quantum mechanics. We revisit this thought experiment from a modern point of view at a level suitable for undergraduate readership and find that neither Einstein nor Bohr was right. Instead, this thought experiment should be thought of as an early example of a system demonstrating nonlocal "EPR" quantum correlations, five years before the famous Einstein-Podolsky-Rosen paper.Comment: 11 pages, revised, accepted for publication in Eur. J. Phy

Quantum diffusion on a cyclic one dimensional lattice

The quantum diffusion of a particle in an initially localized state on a cyclic lattice with N sites is studied. Diffusion and reconstruction time are calculated. Strong differences are found for even or odd number of sites and the limit N->infinit is studied. The predictions of the model could be tested with micro - and nanotechnology devices.Comment: 17 pages, 5 figure

The benefits of active portfolio management. A reform proposal to Michoacan State’s Public Pension Fund Office

El presente artículo estudia el contexto legal y administrativo de uno de los fondos de pensiones de beneficio definido políticamente más relevantes en México, la Dirección de Pensiones Civiles del Estado de Michoacán. Como consecuencia de esto, se hace la propuesta de una política, estructura y proceso de gestión activa de carteras para su reserva técnica. Para probar la pertinencia de la propuesta, se realizó una simulación de eventos discretos con tres tipos de matrices de covarianzas, empleando el modelo Markowitz- Tobin-Sharpe-Lintner. Los resultados demuestran que se superan los objetivos actuariales planteados y se logra incrementar, como consecuencia, el periodo de suficiencia financiera del plan de pensiones

Classification of Generalized Symmetries for the Vacuum Einstein Equations

A generalized symmetry of a system of differential equations is an infinitesimal transformation depending locally upon the fields and their derivatives which carries solutions to solutions. We classify all generalized symmetries of the vacuum Einstein equations in four spacetime dimensions. To begin, we analyze symmetries that can be built from the metric, curvature, and covariant derivatives of the curvature to any order; these are called natural symmetries and are globally defined on any spacetime manifold. We next classify first-order generalized symmetries, that is, symmetries that depend on the metric and its first derivatives. Finally, using results from the classification of natural symmetries, we reduce the classification of all higher-order generalized symmetries to the first-order case. In each case we find that the generalized symmetries are infinitesimal generalized diffeomorphisms and constant metric scalings. There are no non-trivial conservation laws associated with these symmetries. A novel feature of our analysis is the use of a fundamental set of spinorial coordinates on the infinite jet space of Ricci-flat metrics, which are derived from Penrose's ``exact set of fields'' for the vacuum equations.Comment: 57 pages, plain Te

Molecular evidence of incipient speciation within Anopheles gambiae s.s. in West Africa

We karyotyped and identified by polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) analysis Anopheles gambiae s.s. samples collected in several African countries. The data show the existence of two non-panmictic molecular forms, named S and M, whose distribution extended from forest to savannahs, Mosquitoes of the S and M forms are homosequential standard for chromosome-2 inversions in forest areas. In dry savannahs, S is characterized mainly by inversion polymorphisms typical of Savanna and Bamako chromosomal forms, while M shows chromosome-2 arrangements typical of Mopti and/or Savanna and/or Bissau, depending on its geographical origin. Chromosome-2 inversions therefore seem to be involved in ecotypic adaptation rather than in mate-recognition systems. Strong support for the reproductive isolation of S and M in Ivory Coast comes from the observation that the kdr allele is found at high frequencies in S specimens and not at all in chromosomal identical M specimens. However, the kdr allele does not segregate with molecular forms in Benin

The cost of doing nothing: Testing the benefits of water disposal risk reduction with water management Activism investing in Latin America

El costo de hacer nada: Una prueba de los beneficios de la reducción del riesgo de disposición de agua por medio de inversión activista en aguaObjetivo: Se responde la pregunta ¿cuál sería el desempeño de un inversionista si invierte solo en compañías con un adecuado manejo de agua en Latino Amética? Metodología: Se emplea la razón de consumo de agua entre ingresos (WTR) para medir la calidad de las políticas de manejo de agua en la empresa. También simula el desempeño de un inversionista invertido principalemente en empresas con el mejor WTR (del 6 de enero del 2005 al 20 de abril del 2022). Resultados: Al comparar el portafolio simulado contra el de mercado, los resultados sugieren que ambos tienen un desempeño similar en el corto plazo. En el largo plazo, las pruebas evidencian que el portafolio WTR tiene un riesgo sistemático menor (beta de 0.26), y su desempeño es más estable (media-varianza eficiente). Los resultados controlan el impacto de fluctuaciones cambiarias en algunos paises latinoamericanos. Conclusiones: Los resultados pueden ser de utilidad para inversionistas activistas de consumo de agua, motivar mejores prácticas de manejo de agua en las empresas y reducir el riesgo de disposición de agua en años venideros.Objective: This paper answers What would the performance of an investor be if she or he invested only in public companies with proper water management practices in Latin America (LATAM)? Methodology: The research uses the water-to-revenues (WTR) ratio to measure water management quality. It simulates the performance of an investor invested mainly in companies with the best WTR (from January 6th, 2005, to Abril 20, 2022). Results: Comparing the simulated portfolio’s performance against a broad market portfolio, the results suggest that both portfolios have similar performance in the short term. In the long term, the tests found that the WTR has a low systematic (market) risk (beta of 0.26), and its performance is more stable (mean-variance efficient) than the market portfolio. The tests also control the impact of some LATAM currencies’ depreciation. Conclusions: The results could be useful for investors to engage in water management activism through investing, motivate companies to engage in better water management practices, and reduce the future risk that water disposal represents to the world in years to come

Promoting post-stroke recovery through focal or whole body vibration: criticisms and prospects from a narrative review

Objective: Several focal muscle vibration (fMV) and whole body vibration (WBV) protocols have been designed to promote brain reorganization processes in patients with stroke. However, whether fMV and WBV should be considered helpful tools to promote post-stroke recovery remains still largely unclear. Methods: We here achieve a comprehensive review of the application of fMV and WBV to promote brain reorganization processes in patients with stroke. By first discussing the putative physiological basis of fMV and WBV and then examining previous observations achieved in recent randomized controlled trials (RCT) in patients with stroke, we critically discuss possible strength and limitations of the currently available data. Results: We provide the first systematic assessment of fMV studies demonstrating some improvement in upper and lower limb functions, in patients with chronic stroke. We also confirm and expand previous considerations about the rather limited rationale for the application of current WBV protocols in patients with chronic stroke. Conclusion: Based on available information, we propose new recommendations for optimal stimulation parameters and strategies for recruitment of specific stroke populations that would more likely benefit from future fMV or WBV application, in terms of speed and amount of post-stroke functional recovery