203 research outputs found
Multiatom Quantum Coherences in Micromasers as Fuel for Thermal and Nonthermal Machines
In this paper we address the question: To what extent is the quantum state
preparation of multiatom clusters (before they are injected into the microwave
cavity) instrumental for determining not only the kind of machine we may
operate but also the quantitative bounds of its performance? Figuratively
speaking, if the multiatom cluster is the "crude oil", the question is: Which
preparation of the cluster is the refining process that can deliver a
"gasoline" with a "specific octane"? We classify coherences or quantum
correlations among the atoms according to their ability to serve as (i) fuel
for nonthermal machines corresponding to atomic states whose coherences
displace or squeeze the cavity field, as well as cause its heating; and (ii)
fuel which is purely "combustible", i.e., corresponds to atomic states that
only allow for heat and entropy exchange with the field and can energize a
proper heat engine. We identify highly promising multiatom states for each kind
of fuel and propose viable experimental schemes for their implementation.Comment: 13 pages, 8 figure
Work and Heat Value of Bound Entanglement
Entanglement has recently been recognized as an energy resource which can
outperform classical resources if decoherence is relatively low. Multi-atom
entangled states can mutate irreversibly to so called bound entangled (BE)
states under noise. Resource value of BE states in information applications has
been under critical study and a few cases where they can be useful have been
identified. We explore the energetic value of typical BE states. Maximal work
extraction is determined in terms of ergotropy. Since the BE states are
non-thermal, extracting heat from them is less obvious. We compare single and
repeated interaction schemes to operationally define and harvest heat from BE
states. BE and free entangled (FE) states are compared in terms of their
ergotropy and maximal heat values. Distinct roles of distillability in work and
heat values of FE and BE states are pointed out. Decoherence effects in
dynamics of ergotropy and mutation of FE states into BE states are examined to
clarify significance of the work value of BE states. Thermometry of
distillability of entanglement using micromaser cavity is proposed.Comment: 22 pages, 10 figure
An optimal stopping problem for spectrally negative Markov additive processes
Previous authors have considered optimal stopping problems driven by the
running maximum of a spectrally negative L\'evy process , as well as of a
one-dimensional diffusion. Many of the aforementioned results are either
implicitly or explicitly dependent on Peskir's maximality principle. In this
article, we are interested in understanding how some of the main ideas from
these previous works can be brought into the setting of problems driven by the
maximum of a class of Markov additive processes (more precisely Markov
modulated L\'evy processes). Similarly to previous works in the L\'evy setting,
the optimal stopping boundary is characterised by a system of ordinary
first-order differential equations, one for each state of the modulating
component of the Markov additive process. Moreover, whereas scale functions
played an important role in the previously mentioned work, we work instead with
scale matrices for Markov additive processes here. We exemplify our
calculations in the setting of the Shepp-Shiryaev optimal stopping problem, as
well as a family of capped maximum optimal stopping problems.Comment: 31 page
Koncentracije serumskog prokalcitonina i C-reaktivnog proteina u pasa s degenerativnom bolešću mitralnog zaliska i infektivnim endokarditisom
This study aimed to investigate the clinical significance of serum C-reactive protein (CRP) and procalcitonin (PCT) concentrations in dogs with degenerative mitral valve disease (DMVD) and infective endocarditis. It also aimed to evaluate whether there is a relationship between the degree of disease and serum PCT and CRP concentrations. A total of 100 dogs with MVD were prospectively recruited into the study. According to clinical/laboratory signs and echocardiography, the dogs were divided into infective and degenerative groups. The degenerative group was also classified into four stages based on the American College of Veterinary Internal Medicine (ACVIM) guidelines (Stages A-D). Serum PCT and CRP concentrations were determined with dog-specific commercial test kits. The serum CRP (P<0.05) and PCT (P<0.001) concentrations in the infective group were significantly higher than the degenerative group. In the degenerative group, the serum CRP concentration of stage D dogs was significantly higher than the other stages (P<0.001), and the degree of disease correlated significantly positively with serum CRP concentration (r=0.531 P=0.000). In conclusion, serum CRP and PCT concentrations may aid traditional diagnostic techniques to differentiate infective and degenerative mitral valve disease. This study also demonstrated that serum CRP concentrations were elevated in Stage D dogs, and that there is a positive correlation between the degree of disease and serum CRP concentration. This can be useful in determining the severity of the inflammatory state in dogs with DMVD.Cilj rada bio je istražiti kliničku važnost serumskih koncentracija C-reaktivnog proteina (CRP) i prokalcitonina (PCT) u pasa s degenerativnom bolešću mitralnog zaliska (DMVD) i infektivnim endokarditisom. Također, cilj je bio i procijeniti postoji li povezanost između stupnja bolesti i serumskih koncentracija PCT-a i CRP-a. U prospektivno istraživanje uključeno je ukupno je 100 pasa s MVD-om. Prema kliničko laboratorijskim znakovima i ehokardiografiji psi su podijeljeni u skupinu s infektivnom i skupinu s degenerativnom bolešću. Psi s degenerativnom bolešću razvrstani su u četiri stadija (A-D) prema smjernicama American College of Veterinary Internal Medicine (ACVIM). Koncentracije serumskog PCT-a i CRP-a određene su komercijalnim testnim setovima specifičnima za pse. Koncentracije serumskog CRP-a i PCT-a u skupini pasa s infektivnom bolešću bile su znakovito više (P<0,05 i P<0,001) nego one u skupini pasa s degenerativnom bolešću. U skupini s degenerativnom bolešću serumske koncentracije CRP-a u pasa sa stadijem D bile su znakovito više nego u pasa s ostalim stadijima (P<0,001). Stupanj bolesti bio je u znakovitoj pozitivnoj korelaciji sa serumskim koncentracijama CRP-a (r = 0,531, P=0,000). Zaključno, serumske koncentracije CRP-a i PCT-a mogu pomoći tradicionalnim dijagnostičkim metodama u razlikovanju infektivne i degenerativne bolesti mitralnog zaliska. Istraživanje je pokazalo i povišene serumske koncentracije CRP-a u pasa sa stadijem D te pozitivnu korelaciju između stupnja bolesti i koncentracije CRP-a. Navedeno može biti korisno pri procjeni težine upalnog stanja u pasa s DMVD-om
Temperature control in dissipative cavities by entangled dimers
We show that the temperature of a cavity field can be drastically varied by
its interaction with suitably-entangled atom pairs (dimers) traversing the
cavity under realistic atomic decoherence. To this end we resort to the
hitherto untapped resource of naturally entangled dimers whose state can be
simply controlled via molecular dissociation, collisions forming the dimer, or
unstable dimers such as positronium. Depending on the chosen state of the
dimer, the cavity-field mode can be driven to a steady-state temperature that
is either much lower or much higher than the ambient temperature, despite
adverse effects of cavity loss and atomic decoherence. Entangled dimers enable
much broader range of cavity temperature control than single `phaseonium' atoms
with coherently-superposed levels. Such dimers are shown to constitute highly
caloric fuel that can ensure high efficiency or power in photonic thermal
engines. Alternatively, they can serve as controllable thermal baths for
quantum simulation of energy exchange in photosynthesis or quantum annealing.Comment: 12 pages, 6 figure
A price to pay: Turkish and American retaliation for threats to personal and family honor
Two studies investigated retaliatory responses to actual honor threats among members of an honor culture (Turkey) and a dignity culture (northern U.S.). The honor threat in these studies was based on previous research which has shown that honesty is a key element of the conception of honor and that accusations of dishonesty are threatening to one’s honor. In both studies, participants wrote an essay describing the role of honesty in their lives and received feedback on their essay accusing them of being dishonest (vs. neutral feedback). Turkish participants retaliated more strongly than did northern U.S. participants against the person who challenged their honesty by assigning him/her to solve more difficult tangrams over easy ones (Study 1) and by choosing sensory tasks of a higher level of intensity to complete (Study 2). Study 2 added a relational honor condition, in which participants wrote about honesty in their parents’ lives and examined the role of individual differences in honor values in retaliation. Endorsement of honor values predicted retaliation among Turkish participants in both the personal and relational honor conditions, but not among northern U.S. participants
Modeling the Effect of Channel Tapering on the Pressure Drop and Flow Distribution Characteristics of Interdigitated Flow Fields in Redox Flow Batteries
This article belongs to the Special Issue CFD Applications in Energy Engineering Research and Simulation.Optimization of flow fields in redox flow batteries can increase performance and efficiency, while reducing cost. Therefore, there is a need to establish a fundamental understanding on the connection between flow fields, electrolyte flow management and electrode properties. In this work, the flow distribution and pressure drop characteristics of interdigitated flow fields with constant and tapered cross-sections are examined numerically and experimentally. Two simplified 2D along-the-channel models are used: (1) a CFD model, which includes the channels and the porous electrode, with Darcy’s viscous resistance as a momentum sink term in the latter; and (2) a semi-analytical model, which uses Darcy’s law to describe the 2D flow in the electrode and lubrication theory to describe the 1D Poiseuille flow in the channels, with the 2D and 1D sub-models coupled at the channel/electrode interfaces. The predictions of the models are compared between them and with experimental data. The results show that the most influential parameter is γ , defined as the ratio between the pressure drop along the channel due to viscous stresses and the pressure drop across the electrode due to Darcy’s viscous resistance. The effect of Re in the channel depends on the order of magnitude of γ , being negligible in conventional cells with slender channels that use electrodes with permeabilities in the order of 10−12m2 and that are operated with moderate flow rates. Under these conditions, tapered channels can enhance mass transport and facilitate the removal of bubbles (from secondary reactions) because of the higher velocities achieved in the channel, while being pumping losses similar to those of constant cross-section flow fields. This agrees with experimental data measured in a single cell operated with aqueous vanadium-based electrolytes.This work was supported by the research project PID2019-106740RB-I00 of the Spanish Ministry of Science, Innovation and Universities, the project PEM4ENERGY-CM-UC3M funded by the call "Programa de apoyo a la realización de proyectos interdisciplinares de I+D para jóvenes investigadores de la Universidad Carlos III de Madrid 2019-2020" under the frame of the "Convenio Plurianual Comunidad de Madrid-Universidad Carlos III de Madrid", and the Energy and Environment Research Grant of the Spanish Iberdrola Foundation
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Beliefs about sleep paralysis in Turkey: Karabasan attack.
The present study examined explanations of sleep paralysis (SP) in Turkey. The participants were 59 college students recruited in İstanbul, Turkey, who had experienced SP at least once in their lifetime. Participants were administered the Sleep Paralysis Experiences and Phenomenology Questionnaire (SP-EPQ) in an interview. When asked whether they had heard of a name for SP, the vast majority (88%) mentioned the "Karabasan"-a spirit-like creature rooted in Turkish folk tradition. Seventeen percent of the participants believed that their SP might have been caused by this supernatural creature. Thirty-seven percent of participants applied various supernatural and religious methods to prevent future SP attacks such as dua (supplicating to God), reciting the Quran, and wearing a musqa (a type of talisman inscribed with Quranic verses). Case studies are presented to illustrate these findings. The Karabasan constitutes a culturally specific, supernatural interpretation of the phenomenology of SP in Turkey
Cultures of honor
Cultures of honor developed in contexts in which a person’s livelihood was easily stolen (such as a herd of animals) and the rule of law was weak. In such contexts, men were required to develop a reputation for toughness and willingness to retaliate quickly and aggressively when threatened, so that others would not consider stealing their property. Consequently, cultures of honor have developed ideologies, norms, and practices that reinforce the importance of maintaining social respect through aggressive means if necessary. In this chapter, we first briefly review the initial work by anthropologists, sociologists and historians that described cultures of honor in the Mediterranean region and southern US states. This early work formed the foundation of research by Nisbett, Cohen, and their colleagues, who carefully articulated a psychological theory of how concerns for honor may explain higher rates of aggression and violence in southern US states compared to northern states. We then summarize research on components of honor, behavioral and psychological consequences of honor, and socialization practices that maintain cultures of honor. We finish by discussing possible future directions and methodological considerations in research on cultures of honor. This research has extended the scope of cultural psychology by going beyond the more common east-west comparisons; it has the potential to help explain behavior of groups that have not been widely studied by social psychologists
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