Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 18 de 18
Filtrar
1.
Health Econ ; 33(5): 929-951, 2024 May.
Artículo en Inglés | MEDLINE | ID: mdl-38278781

RESUMEN

Using a representative survey with 1317 individuals and 12,815 moral decisions, we elicit Swedish citizens' preferences on how algorithms for self-driving cars should be programmed in cases of unavoidable harm to humans. Participants' choices in different dilemma situations (treatments) show that, at the margin, the average respondent values the lives of passengers and pedestrians equally when both groups are homogeneous and no group is to blame for the dilemma. In comparison, the respondent values the lives of passengers more when the pedestrians violate a social norm, and less when the pedestrians are children. Furthermore, we explain why the average respondent in the control treatment needs to be compensated with two to six passengers spared in order to sacrifice the first pedestrian, even though she values the lives of passengers and pedestrians equally at the margin. We conclude that respondents' choices are highly contextual and consider the age of the persons involved and whether these persons have complied with social norms.


Asunto(s)
Automóviles , Peatones , Femenino , Niño , Humanos , Accidentes de Tránsito , Principios Morales , Encuestas y Cuestionarios
2.
Nucleic Acids Res ; 42(2): 952-67, 2014 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-24163258

RESUMEN

Mitochondrial DNA (mtDNA) is organized in discrete protein-DNA complexes, nucleoids, that are usually considered to be mitochondrial-inner-membrane associated. Here we addressed the association of replication factors with nucleoids and show that endogenous mtDNA helicase Twinkle and single-stranded DNA-binding protein, mtSSB, co-localize only with a subset of nucleoids. Using nucleotide analogs to identify replicating mtDNA in situ, the fraction of label-positive nucleoids that is Twinkle/mtSSB positive, is highest with the shortest labeling-pulse. In addition, the recruitment of mtSSB is shown to be Twinkle dependent. These proteins thus transiently associate with mtDNA in an ordered manner to facilitate replication. To understand the nature of mtDNA replication complexes, we examined nucleoid protein membrane association and show that endogenous Twinkle is firmly membrane associated even in the absence of mtDNA, whereas mtSSB and other nucleoid-associated proteins are found in both membrane-bound and soluble fractions. Likewise, a substantial amount of mtDNA is found as soluble or loosely membrane bound. We show that, by manipulation of Twinkle levels, mtDNA membrane association is partially dependent on Twinkle. Our results thus show that Twinkle recruits or is assembled with mtDNA at the inner membrane to form a replication platform and amount to the first clear demonstration that nucleoids are dynamic both in composition and concurrent activity.


Asunto(s)
ADN Helicasas/metabolismo , Replicación del ADN , ADN Mitocondrial/biosíntesis , Membranas Mitocondriales/metabolismo , Proteínas Mitocondriales/metabolismo , Línea Celular , Células Cultivadas , ADN Helicasas/análisis , ADN Helicasas/antagonistas & inhibidores , ADN Mitocondrial/metabolismo , Proteínas de Unión al ADN/metabolismo , Humanos , Membranas Mitocondriales/química , Proteínas Mitocondriales/análisis , Proteínas Mitocondriales/antagonistas & inhibidores
4.
Nat Hum Behav ; 6(6): 774-781, 2022 06.
Artículo en Inglés | MEDLINE | ID: mdl-35301468

RESUMEN

The law of supply is a fundamental principle of economics and states that any increase in price will increase the quantity supplied. In the case of prosocial behaviour, however, increasing rewards have reduced supply, posing a challenge to standard economic theory. Attempts to study such 'crowding-out' have been limited by their small scale and the inherent difficulties posed by calibration of experimental tests. We analyse a large-scale natural experiment in the environmental domain consisting of 20,370 independent observations derived from aggregation of approximately 27 million individual decisions. We find that aggregate supply of prosocial behaviour is 's-shaped', demonstrating how attempts to increase prosocial behaviour using monetary rewards can be counter-productive. Our study shows that results derived from a small set of data points collected from an underlying s-shaped data-generating process are vulnerable to misinterpretation, and that proxy measures of intrinsic motivation ought to be collected to ensure theoretical advance.


Asunto(s)
Altruismo , Recompensa , Humanos , Motivación
5.
PLoS One ; 17(11): e0277210, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-36346790

RESUMEN

In this paper, we present evidence from a lab-in-the-field experiment of the effects of the Chinese one-child policy on adults in China who were born just before and after the introduction of the policy. We measure risk, uncertainty, and time preferences, as well as subjects' preferences in the social domain, i.e., concerning competitiveness, cooperation, and bargaining. We sampled people from three Chinese provinces born both before and after the introduction of the policy in 1979. We utilize the fact that the one-child policy was introduced at different times and with different degrees of strictness in different provinces. Overall, we find a statistically significant effect only on risk and uncertainty aversion and not on any other preferences in the experiments: Those born after the introduction of the one-child policy are less risk and uncertainty averse. These results hold for various robustness checks and heterogeneity tests. Hence, our results do not confirm the general wisdom and stereotype of only-children in China being "little emperors."


Asunto(s)
Política de Planificación Familiar , Adulto , Humanos , China
6.
Eur J Neurosci ; 33(9): 1647-55, 2011 May.
Artículo en Inglés | MEDLINE | ID: mdl-21453290

RESUMEN

Synaptic plasticity is regarded as the major candidate mechanism for synaptic information storage and memory formation in the hippocampus. Mitogen-activated protein kinases have recently emerged as an important regulatory factor in many forms of synaptic plasticity and memory. As one of the subfamilies of mitogen-activated protein kinases, extracellular-regulated kinase is involved in the in vitro induction of long-term potentiation (LTP), whereas p38 mediates metabotropic glutamate receptor-dependent long-term depression (LTD) in vitro. Although c-Jun N-terminal kinase (JNK) has also been implicated in synaptic plasticity, the in vivo relevance of JNK activity to different forms of synaptic plasticity remains to be further explored. We investigated the effect of inhibition of JNK on different forms of synaptic plasticity in the dentate gyrus of freely behaving adult rats. Intracereboventricular application of c-Jun N-terminal protein kinase-inhibiting peptide (D-JNKI) (96 ng), a highly selective JNK inhibitor peptide, did not affect basal synaptic transmission but reduced neuronal excitability with a higher dose (192 ng). Application of D-JNKI, at a concentration that did not affect basal synaptic transmission, resulted in reduced specific phosphorylation of the JNK substrates postsynaptic density 95kD protein (PSD 95) and c-Jun, a significant enhancement of LTD and a facilitation of short-term depression into LTD. Both LTP and short-term potentiation were unaffected. An inhibition of depotentiation (recovery of LTP) occurred. These data suggest that suppression of JNK-dependent signalling may serve to enhance synaptic depression, and indirectly promote LTP through impairment of depotentiation.


Asunto(s)
Conducta Animal/efectos de los fármacos , Hipocampo/fisiología , Proteínas Quinasas JNK Activadas por Mitógenos/antagonistas & inhibidores , Potenciación a Largo Plazo/fisiología , Depresión Sináptica a Largo Plazo/fisiología , Péptidos/farmacología , Animales , Electrofisiología , Proteínas Quinasas JNK Activadas por Mitógenos/metabolismo , Potenciación a Largo Plazo/efectos de los fármacos , Depresión Sináptica a Largo Plazo/efectos de los fármacos , Masculino , Ratas , Ratas Wistar , Transmisión Sináptica/efectos de los fármacos , Proteínas Quinasas p38 Activadas por Mitógenos/metabolismo
7.
Health Econ ; 20(6): 723-36, 2011 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-20575149

RESUMEN

Using a random sample of individuals in rural Bangladesh, this paper investigates people's ethical preferences regarding relative values of lives when it comes to saving lives of individuals of different ages. By assuming that an individual has preferences concerning different states of the world, and that these preferences can be described by an individual social welfare function, the individuals' preferences for life-saving programs are elicited using a pair-wise choice experiment involving different life-saving programs. In the analyses, we calculate the social marginal rates of substitution between saved lives of people of different ages. We also test whether people have preferences for saving more life-years rather than only saving lives. In particular, we test and compare the two hypotheses that only lives matter and that only life-years matter. The results indicate that the value of a saved life decreases rapidly with age and that people have strong preferences for saving life-years rather than lives per se. Overall, the results clearly show the importance of the number of life-years saved in the valuation of life.


Asunto(s)
Conducta de Elección/ética , Población Rural , Valor de la Vida , Adulto , Factores de Edad , Anciano , Anciano de 80 o más Años , Bangladesh , Humanos , Masculino , Persona de Mediana Edad , Modelos Estadísticos , Valores Sociales , Adulto Joven
8.
Econ Hum Biol ; 33: 1-14, 2019 05.
Artículo en Inglés | MEDLINE | ID: mdl-30591424

RESUMEN

We investigate the relationship between relative concerns with respect to income and the quantity and quality of sleep using a 6-year panel dataset on the sleep behavior of people in Germany. We find a substantial negative association between relative income and number of hours of sleep and satisfaction with sleep, i.e., sleep quality, whereas there is no particular association between absolute level of income and sleep quantity and quality. A 10-percent increase in the income of relevant others is associated with 6-8 min decrease in a person's weekly amount of sleep on average, yet this effect is particularly strong among the relatively deprived, i.e., upward comparers, as this group shows a corresponding decrease in sleeping time of 10-12 min/week. These findings are highly robust to several specification checks, including measures of relative concerns, reference group, income inequality, and local price differences. The heterogeneity analysis reveals that the relationship is mainly driven by people with relatively fewer working hours, a higher demand for household production and leisure activities, and lower physical health and well-being.


Asunto(s)
Renta , Trastornos del Sueño-Vigilia/epidemiología , Sueño/fisiología , Adulto , Anciano , Femenino , Alemania/epidemiología , Estado de Salud , Humanos , Actividades Recreativas , Masculino , Salud Mental/estadística & datos numéricos , Persona de Mediana Edad , Factores Socioeconómicos , Factores de Tiempo , Trabajo/estadística & datos numéricos , Adulto Joven
9.
PLoS One ; 14(5): e0212747, 2019.
Artículo en Inglés | MEDLINE | ID: mdl-31112534

RESUMEN

We propose a novel laboratory experiment to document the pressure to share income within social networks in Africa. We find that the redistributive pressure exerted via the possibility of receiving a claim increases altruism, while the possibility of hiding from such claim reduces it. Our results indicate that sharing norms are crucial drivers of giving to other members of the network. We also find that pressure to share has a detrimental effect on the undertaking of profitable but risky investments.


Asunto(s)
Altruismo , Difusión de la Información , Conducta Social , Toma de Decisiones , Femenino , Humanos , Masculino , Modelos Teóricos , Red Social , Normas Sociales , Tanzanía/epidemiología
10.
J Health Econ ; 27(3): 739-52, 2008 May.
Artículo en Inglés | MEDLINE | ID: mdl-18164772

RESUMEN

We develop a theoretical model of the ethical preferences of individuals, combining individual social welfare functions and random utility theory. The model is applied by conducting a choice experiment regarding safety-enhancing road investments that target different age groups and road user types. The relative value of a saved life is found to decrease with age, such that the present value of a saved life-year is almost independent of age at a pure rate of time preference of a few percent. Moreover, a saved pedestrian is consistently valued higher than a saved car driver of the same age.


Asunto(s)
Modelos Teóricos , Valor de la Vida , Factores de Edad , Altruismo , Conducta de Elección , Humanos , Seguridad/economía , Transportes/economía
11.
Mitochondrion ; 7(5): 311-21, 2007 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-17698423

RESUMEN

Mitochondrial DNA is arranged in nucleoprotein complexes, or nucleoids. Nucleoid proteins include not only factors involved in replication and transcription but also structural proteins required for mitochondrial DNA maintenance. Although several nucleoid proteins have been identified and characterized in yeast over the course of the past decade, little was known of mammalian mitochondrial nucleoids until recently. Two publications in the past year have expanded considerably the pool of putative mammalian mitochondrial nucleoid proteins; and analysis of one of the candidates, ATAD3p, suggests that mitochondrial nucleoid formation and division are orchestrated, not random, events.


Asunto(s)
Proteínas de Unión al ADN/fisiología , Mitocondrias/fisiología , Nucleoproteínas/genética , ATPasas Asociadas con Actividades Celulares Diversas , Adenosina Trifosfatasas , Animales , Células Cultivadas , Replicación del ADN/fisiología , ADN Mitocondrial/metabolismo , Humanos , Proteínas de la Membrana , Enfermedades Mitocondriales/fisiopatología , Membranas Mitocondriales/fisiología , Proteínas Mitocondriales , Saccharomyces cerevisiae/ultraestructura
12.
Methods Mol Biol ; 372: 17-32, 2007.
Artículo en Inglés | MEDLINE | ID: mdl-18314715

RESUMEN

Mitochondria are almost ubiquitous organelles in Eukaryota. They are highly dynamic and often complex structures in the cell. The mammalian mitochondrial proteome is predicted to comprise as many as 2000-2500 different proteins. Determination of the subcellular localization of any newly identified protein is one of the first steps toward unraveling its biological function. For most mitochondrial proteins, this can now be done relatively easily by cloning a complementary deoxyribonucleic acid of interest in frame with an additional sequence for a fluorescent or nonfluorescent protein tag. Transfection and subsequent visualization, either by direct fluorescence microscopy or by indirect immunofluorescence microscopy, will give the first clue to mitochondrial localization. In combination with a fluorescent "marker" dye, the mitochondrial localization can be confirmed. This chapter describes some of the methods used in determining mitochondrial protein localization, which can also be used to study dynamics of mitochondria or individual mitochondrial proteins or protein complexes.


Asunto(s)
Fraccionamiento Celular/métodos , Mitocondrias/metabolismo , Proteínas Mitocondriales/metabolismo , Fijación del Tejido/métodos , Animales , Supervivencia Celular , Colorantes , ADN Mitocondrial , Proteínas Fluorescentes Verdes , Células HeLa , Humanos , Ratones , Transfección , beta-Galactosidasa
13.
Ultramicroscopy ; 99(4): 235-45, 2004 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-15149718

RESUMEN

We describe in this paper a home-built scanning-probe setup that combines the high spatial resolution of a commercial atomic-force microscope (AFM) with the high sensitivity and the discriminative power of a confocal two-photon fluorescence microscope. This scheme offers the ability of acquiring simultaneous, directly correlated topography and optical images with high sensitivity and resolution, and was successfully tested using model systems, such as dye-loaded latex beads. As a first biological application, we studied the (un)stacking of grana membranes in the envelope-free plant chloroplasts. The topographs showed two grana layers attached together in a "native unit" 15-16 nm thick and 4 nm protrusions on their surface, which we assign to Photosystem II reaction center. The optical imaging did not resolve single photosynthetic proteins, but helped in identifying the grana and indicated that the protein conformation and the chromophore binding are intact. Furthermore, our instrument allowed a direct comparison between the cell morphology and the distribution of the signaling protein H-Ras in living cells, i.e. mouse fibroblasts. With our approach the nanometer-scale resolving power of AFM is improved with the chemical identification capabilities of optical techniques, thus opening up interesting possibilities in various areas of research, including material and life sciences.


Asunto(s)
Microscopía de Fuerza Atómica , Microscopía Confocal , Microscopía Fluorescente , Animales , Línea Celular , Cloroplastos/ultraestructura , Fibroblastos/ultraestructura , Ratones , Microscopía de Fuerza Atómica/instrumentación , Fotones
14.
Mol Cell Biol ; 29(15): 4274-82, 2009 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-19487465

RESUMEN

Dna2 is a highly conserved helicase/nuclease that in yeast participates in Okazaki fragment processing, DNA repair, and telomere maintenance. Here, we investigated the biological function of human Dna2 (hDna2). Immunofluorescence and biochemical fractionation studies demonstrated that hDna2 was present in both the nucleus and the mitochondria. Analysis of mitochondrial hDna2 revealed that it colocalized with a subfraction of DNA-containing mitochondrial nucleoids in unperturbed cells. Upon the expression of disease-associated mutant forms of the mitochondrial Twinkle helicase which induce DNA replication pausing/stalling, hDna2 accumulated within nucleoids. RNA interference-mediated depletion of hDna2 led to a modest decrease in mitochondrial DNA replication intermediates and inefficient repair of damaged mitochondrial DNA. Importantly, hDna2 depletion also resulted in the appearance of aneuploid cells and the formation of internuclear chromatin bridges, indicating that nuclear hDna2 plays a role in genomic DNA stability. Together, our data indicate that hDna2 is similar to its yeast counterpart and is a new addition to the growing list of proteins that participate in both nuclear and mitochondrial DNA maintenance.


Asunto(s)
Núcleo Celular/genética , ADN Helicasas/metabolismo , Replicación del ADN/genética , ADN Mitocondrial/genética , Western Blotting , Línea Celular , Núcleo Celular/metabolismo , Citoplasma/metabolismo , Daño del ADN , ADN Helicasas/genética , Reparación del ADN , Técnica del Anticuerpo Fluorescente , Células HeLa , Humanos , Inmunoprecipitación , Microscopía Confocal , Mitocondrias/metabolismo , Proteínas Mitocondriales , Mutación , Interferencia de ARN
15.
Photosynth Res ; 86(1-2): 101-11, 2005 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-16172929

RESUMEN

Chlorosomes are the light-harvesting organelles in photosynthetic green bacteria and typically contain large amounts of bacteriochlorophyll (BChl) c in addition to smaller amounts of BChl a, carotenoids, and several protein species. We have isolated vestigial chlorosomes, denoted carotenosomes, from a BChl c-less, bchK mutant of the green sulfur bacterium Chlorobium tepidum. The physical shape of the carotenosomes (86 +/- 17 nm x 66 +/- 13 nm x 4.3 +/- 0.8 nm on average) was reminiscent of a flattened chlorosome. The carotenosomes contained carotenoids, BChl a, and the proteins CsmA and CsmD in ratios to each other comparable to their ratios in wild-type chlorosomes, but all other chlorosome proteins normally found in wild-type chlorosomes were found only in trace amounts or were not detected. Similar to wild-type chlorosomes, the CsmA protein in the carotenosomes formed oligomers at least up to homo-octamers as shown by chemical cross-linking and immunoblotting. The absorption spectrum of BChl a in the carotenosomes was also indistinguishable from that in wild-type chlorosomes. Energy transfer from the bulk carotenoids to BChl a in carotenosomes was poor. The results indicate that the carotenosomes have an intact baseplate made of remarkably stable oligomeric CsmA-BChl a complexes but are flattened in structure due to the absence of BChl c. Carotenosomes thus provide a valuable material for studying the biogenesis, structure, and function of the photosynthetic antennae in green bacteria.


Asunto(s)
Bacterioclorofilas/deficiencia , Carotenoides/metabolismo , Chlorobium/citología , Chlorobium/genética , Orgánulos/química , Orgánulos/metabolismo , Proteínas Bacterianas/química , Proteínas Bacterianas/metabolismo , Carotenoides/química , Fraccionamiento Celular , Chlorobium/química , Chlorobium/ultraestructura , Microscopía de Fuerza Atómica , Microscopía Electrónica , Mutación/genética , Unión Proteica , Análisis Espectral
16.
Health Econ ; 12(4): 281-94, 2003 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-12652515

RESUMEN

This paper discusses different design techniques for stated preference surveys in health economic applications. In particular, we focus on different design techniques, i.e. how to combine the attribute levels into alternatives and choice sets, for choice experiments. Design is a vital issue in choice experiments since the combination of alternatives in the choice sets will determine the degree of precision obtainable from the estimates and welfare measures. In this paper we compare orthogonal, cyclical and D-optimal designs, where the latter allows expectations about the true parameters to be included when creating the design. Moreover, we discuss how to obtain prior information on the parameters and how to conduct a sequential design procedure during the actual experiment in order to improve the precision in the estimates. The designs are evaluated according to their ability to predict the true marginal willingness to pay under different specifications of the utility function in Monte Carlo simulations. Our results suggest that the designs produce unbiased estimations, but orthogonal designs result in larger mean square error in comparison to D-optimal designs. This result is expected when using correct priors on the parameters in D-optimal designs. However, the simulations show that welfare measures are not very sensitive if the choice sets are generated from a D-optimal design with biased priors.


Asunto(s)
Actitud Frente a la Salud , Comportamiento del Consumidor/economía , Encuestas de Atención de la Salud/métodos , Modelos Econométricos , Algoritmos , Conducta de Elección , Simulación por Computador , Comportamiento del Consumidor/estadística & datos numéricos , Financiación Personal , Humanos , Método de Montecarlo , Reproducibilidad de los Resultados
17.
Health Econ ; 13(9): 845-57, 2004 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-15362177

RESUMEN

This paper analyses the effect of being insured under the voluntary component of Vietnamese Health Insurance, on patterns of treatment seeking behaviour. A multinomial logit model is estimated using household survey data from three provinces in Vietnam. Decisions regarding both the type of provider sought and type of care received are analysed. Insurance status is treated as both exogenous and endogenous to account for potential selection bias. The results indicate that, overall, insured patients are more likely to use outpatient facilities, and public providers, an effect that is particularly strong at lower income levels.


Asunto(s)
Países en Desarrollo/economía , Seguro de Salud/economía , Aceptación de la Atención de Salud , Pobreza , Adulto , Atención Ambulatoria/economía , Atención Ambulatoria/estadística & datos numéricos , Toma de Decisiones , Femenino , Financiación Gubernamental/organización & administración , Financiación Personal/organización & administración , Encuestas de Atención de la Salud , Gastos en Salud/estadística & datos numéricos , Hospitalización/economía , Humanos , Renta , Funciones de Verosimilitud , Modelos Logísticos , Masculino , Modelos Econométricos , Modelos Psicológicos , Motivación , Programas Nacionales de Salud/economía , Programas Nacionales de Salud/estadística & datos numéricos , Aceptación de la Atención de Salud/psicología , Aceptación de la Atención de Salud/estadística & datos numéricos , Pobreza/economía , Pobreza/psicología , Sector Público/economía , Sector Público/estadística & datos numéricos , Sesgo de Selección , Vietnam
18.
Biophys J ; 86(5): 3121-30, 2004 May.
Artículo en Inglés | MEDLINE | ID: mdl-15111425

RESUMEN

Nanosecond absorption dynamics at approximately 685 nm after excitation of photosystem I (PS I) from Synechocystis sp. PCC 6803 is consistent with electrochromic shift of absorption bands of the Chl a pigments in the vicinity of the secondary electron acceptor A(1). Based on experimental optical data and structure-based simulations, the effective local dielectric constant has been estimated to be between 3 and 20, which suggests that electron transfer in PS I is accompanied by considerable protein relaxation. Similar effective dielectric constant values have been previously observed for the bacterial photosynthetic reaction center and indicate that protein reorganization leading to effective charge screening may be a necessary structural property of proteins that facilitate the charge transfer function. The data presented here also argue against attributing redmost absorption in PS I to closely spaced antenna chlorophylls (Chls) A38 and A39, and suggest that optical transitions of these Chls, along with that of connecting chlorophyll (A40) lie in the range 680-695 nm.


Asunto(s)
Clorofila/química , Cianobacterias/metabolismo , Proteínas del Complejo del Centro de Reacción Fotosintética , Complejo de Proteína del Fotosistema I/química , Electroquímica , Electrones , Modelos Moleculares , Modelos Estadísticos , Espectrofotometría , Factores de Tiempo
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA