7,661 research outputs found
Effect of the spin-orbit interaction on the thermodynamic properties of crystals: The specific heat of bismuth
In recent years, there has been increasing interest in the specific heat
of insulators and semiconductors because of the availability of samples with
different isotopic masses and the possibility of performing \textit{ab initio}
calculations of its temperature dependence using as a starting point the
electronic band structure. Most of the crystals investigated are elemental
(e.g., germanium) or binary (e.g., gallium nitride) semiconductors. The initial
electronic calculations were performed in the local density approximation and
did not include spin-orbit interaction. Agreement between experimental and
calculated results was usually found to be good, except for crystals containing
heavy atoms (e.g., PbS) for which discrepancies of the order of 20% existed at
the low temperature maximum found for . It has been conjectured that
this discrepancies result from the neglect of spin-orbit interaction which is
large for heavy atoms (1.3eV for the valence electrons of
atomic lead). Here we discuss measurements and \textit{ab initio} calculations
of for crystalline bismuth (1.7 eV), strictly speaking a
semimetal but in the temperature region accessible to us ( 2K) acting as a
semiconductor. We extend experimental data available in the literature and
notice that the \textit{ab initio} calculations without spin-orbit interaction
exhibit a maximum at 8K, about 20% lower than the measured one. Inclusion
of spin-orbit interaction decreases the discrepancy markedly: The maximum of
is now only 7% larger than the measured one. Exact agreement is obtained
if the spin-orbit hamiltonian is reduced by a factor of 0.8.Comment: 4 pages, 3 figure
Revealed corruption and electoral accountability in Brazil: How politicians anticipate voting behavior
Governments, civil society organizations, and scholars spend considerable resources implementing and evaluating the effect of anti-corruption interventions. However, decades of cumulative evidence suggest that these interventions rarely lead to the removal of corrupt elected officials from their positions. A recent interpretation of this gap suggests that corrupt politicians often go unpunished because they react to the knowledge of themselves or others being investigated for corruption in unanticipated ways. This dissertation uses data from a long-running anti-corruption program in Brazil to expand on the unintended consequences of anti-corruption interventions that stem from politicians' strategic behavior. The first chapter shows that mayors randomly selected for auditing in the context of this program reduce public spending, particularly in highly visible budget categories, in years close to an election. I argue that this happens because mayors attempt to preserve their reelection chances by signaling fiscal responsibility. The second chapter shows how mayors that are not directly audited, but are in municipalities close to those with mayors exposed as corrupt, tend to seek reelection under different parties more often. As previous accounts of party switching in Brazil suggest, I argue that this occurs because incumbent politicians expect their constituency to react to the news of nearby corruption with increased scrutiny on their own performance in office, which in turn leads them to switch parties in an attempt to secure a better platform for reelection. The question of the effect of exposure to information about nearby corruption opens the door to a broader methodological question of how to capture this type of effect, which is the focus of the third chapter. Research questions in the social sciences usually suggest spillover or interference effects, but rarely provide guidelines on how to model those effects. In fact, theory often suggests many different plausible operationalizations along the same hypothetical pathway. To overcome this difficulty, I propose and illustrate the properties of a model selection approach that uses tools from supervised machine learning to select among alternative operationalizations. As a whole, this dissertation makes two key contributions. First, it shows how politicians' reaction to anti-corruption interventions can stem from an attempt to avoid electoral accountability. Second, by proposing a model selection approach to interference, it expands the applicability of current tools to analyze interference effects to a broader set of research questions
Effect of Power Control Imperfections on the Reverse Link of Cellular CDMA Networks Under Multipath Fading
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Living in Fear: The Dynamics of Extortion in Mexico’s Drug War
Why do drug trafficking organizations (DTOs) sometimes prey on the communities in which they operate but sometimes provide assistance to these communities? What explains their strategies of extortion and co-optation toward civil society? Using new survey data from Mexico, including list experiments to elicit responses about potentially illegal behavior, this article measures the prevalence of extortion and assistance among DTOs. In support of our theory, these data show that territorial contestation among rival organizations produces more extortion and, in contrast, DTOs provide more assistance when they have monopoly control over a turf. The article uncovers other factors that also shape DTOs’ strategies toward the population, including the degree of collaboration with the state, leadership stability and DTO organization, and the value and logistics of the local criminal enterprise
ESTUDIO COMPARATIVO DEL DESARROLLO DE LA ALFABETIZACIÓN EN POBLACIONES DE EDUCACIÓN PRIMARIA Y PREESCOLAR
A comparative study about early literacy of 33 children from elementary school and 27 children from kindergarden was carried out, applying the Instrumento de Observación de los Logros de la Lectoescritura Inicial (Escamilla, Andrade, Basurto y Ruíz, 1996). The purpose of the present work was to characterize the level of early literacy considering the knowledge of the language written in both groups. The groups were evaluated in the first two weeks of the month of September and of October of the school cycle 2011-2012. In the results it was observed that they were only significant differences in the identification of letters. The results are discussed in relation to the concept of early literacy
Swine manure management by hydrothermal carbonization: comparative study of batch and continuous operation
Hydrothermal carbonization (HTC) is considered a promising technology for biomass waste management
without pre-drying. This study explores the potential for swine manure management by comparing batch and
continuous processes, emphasizing the benefits of the continuous mode, particularly for its potential full-scale
application. The continuous process at low temperature (180 ◦C) resulted in a hydrochar with a lower degree
of carbonization compared to the batch process, but similar characteristics were found in both hydrochars at
higher operating temperatures (230–250 ◦C), such as C content (~ 52 wt%), fixed carbon (~ 24 wt%) and higher
calorific value (21 MJ kg− 1
). Thermogravimetric and combustion analyses showed that hydrochars exhibited
characteristics suitable as solid biofuels for industrial use. The process water showed a high content of organic
matter as soluble chemical oxygen demand (7–22 g L− 1
) and total organic carbon (4–10 g L− 1
), although a high
amount of refractory species such as N- and O-containing long aromatic compounds were detected in the process
water from the batch process, while the process water from the continuous process presented more easily
biodegradable compounds such as acids and alcohols, among others. The longer time required to reach operating
temperature in the case of the batch system (longer heating time to reach operating temperature) resulted in
lower H/C and O/C ratios compared to hydrochar from the continuous process. This indicates that the dehydration and decarboxylation reactions of the feedstock play a more important role in the batch process. This
study shows the efficiency of the continuous process to obtain carbonaceous materials suitable for use as biofuel,
providing a solution for swine manure managementAuthors greatly appreciate funding from Spanish MCIN/AEI/
10.13039/501100011033 and European Union "NextGenerationEU/
PRTR" (TED2021-130287B-I00, PDC 2021-120755-I00, and PID 2022-
138632OB-I00) and Grupo Kerbest Company. R.P. Ipiales acknowledges
the financial support from the Community of Madrid (IND2019/AMB17092) and Arquimea Agrotech Compan
Certainty relations between local and nonlocal observables
We demonstrate that for an arbitrary number of identical particles, each
defined on a Hilbert-space of arbitrary dimension, there exists a whole ladder
of relations of complementarity between local, and every conceivable kind of
joint (or nonlocal) measurements. E.g., the more accurate we can know (by a
measurement) some joint property of three qubits (projecting the state onto a
tripartite entangled state), the less accurate some other property, local to
the three qubits, become. We also show that the corresponding complementarity
relations are particularly tight for particles defined on prime dimensional
Hilbert spaces.Comment: 4 pages, no figure
Diseño y optimización de sistemas de transformación y conservación de naranja variedad “Canoneta” de la Serra Nord mallorquina para obtención de naranja IV gama
Este trabajo muestra el efecto de diferentes tipos de procesado sobre la vida útil de naranjas mínimamente procesadas de la variedad “Canoneta”. Las naranjas peladas de manera mecánica o semimanual fueron envasadas en dos atmósferas (vacío parcial y 20% CO2+ 80% N2) y se almacenaron durante 10 días a 4ºC y a 8ºC. Los análisis sensoriales, microbiológicos y físicoquímicos identificaron el pelado semi-manual como el menos idóneo de los métodos de pelado y se estableció 7 días como la vida útil máxima para un producto aceptable desde el punto de vista sensorial
The Arabidopsis thioredoxin TRXh5regulates the S-nitrosylation pattern of the TIRK receptor being both proteins essential in the modulation of defences to Tetranychus urticae
The interaction between plants and phytophagous arthropods encompasses a complex network of molecules, signals, and pathways to overcome defences generated by each interacting organism. Although most of the elements and modulators involved in this interplay are still unidentified, plant redox homeostasis and signalling are essential for the establishment of defence responses. Here, focusing on the response of Arabidopsis thaliana to the spider mite Tetranychus urticae, we demonstrate the involvement in plant defence of the thioredoxin TRXh5, a small redox protein whose expression is induced by mite infestation. TRXh5 is localized in the cell membrane system and cytoplasm and is associated with alterations in the content of reactive oxygen and nitrogen species. Protein S-nitrosylation signal in TRXh5 over-expression lines is decreased and alteration in TRXh5 level produces changes in the JA/SA hormonal crosstalk of infested plants. Moreover, TRXh5 interacts and likely regulates the redox state of an uncharacterized receptor-like kinase, named THIOREDOXIN INTERACTING RECEPTOR KINASE (TIRK), also induced by mite herbivory. Feeding bioassays performed withTRXh5 over-expression plants result in lower leaf damage and reduced egg accumulation after T. urticae infestation than in wild-type (WT) plants. In contrast, mites cause a more severe injury in trxh5 mutant lines where a greater number of eggs accumulates. Likewise, analysis of TIRK-gain and -loss-of-function lines demonstrate the defence role of this receptor in Arabidopsis against T. urticae. Altogether, our findings demonstrate the interaction between TRXh5 and TIRK and highlight the importance of TRXh5 and TIRK in the establishment of effective Arabidopsis defences against spider mite herbivory.Grants PID2020-115219RB-I00, RED2018-102397-T and RyC17MESFB funded by MCIN/AEI/10.13039/501100011033, as appropriate, by “ERDF A way of making Europe” and by the “European Union” supported this work. Grants, SIMQG-263-1HWZ8Q UPM-Banco Santander Universidades, RyC2017-21814 and PRE2018-083375 from MCIN/AEI supported AA, MES and IRD, respectively. The Spanish Ministry of Science and Innovation (MCIN), the State Research Agency (AEI) and the European Regional Development Fund (ERDF; grant MEC-PID2021-122280NB-I00) financed MCRP and LMS. The Government of Canada through the Ontario Research Fund (RE08-067) and the Natural Sciences and Engineering Research Council of Canada (NSERC, RGPIB-2018-04538) supported VG
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