1,628 research outputs found
Phase and Charge reentrant phase transitions in two capacitively coupled Josephson arrays with ultra-small junction
We have studied the phase diagram of two capacitively coupled Josephson
junction arrays with charging energy, , and Josephson coupling energy,
. Our results are obtained using a path integral Quantum Monte Carlo
algorithm. The parameter that quantifies the quantum fluctuations in the i-th
array is defined by . Depending on
the value of , each independent array may be in the semiclassical or
in the quantum regime: We find that thermal fluctuations are important when
and the quantum fluctuations dominate when . We have extensively studied the interplay between vortex and charge
dominated individual array phases. The two arrays are coupled via the
capacitance at each site of the lattices. We find a {\it
reentrant transition} in , at low temperatures, when one of
the arrays is in the semiclassical limit (i.e. ) and the
quantum array has , for the values considered for
the interlayer capacitance. In addition, when , and
for all the inter-layer couplings considered above, a {\it novel} reentrant
phase transition occurs in the charge degrees of freedom, i.e. there is a
reentrant insulating-conducting transition at low temperatures. We obtain the
corresponding phase diagrams and found some features that resemble those seen
in experiments with 2D JJA.Comment: 25 Latex pages including 8 encapsulated poscript figures. Accepted
for publication in Phys. Rev B (Nov. 2004 Issue
Session-based concurrency in Maude:Executable semantics and type checking
Session types are a well-established approach to communication correctness in message-passing processes. Widely studied from a process calculi perspective, here we pursue an unexplored strand and investigate the use of the Maude system for implementing session-typed process languages and reasoning about session-typed process specifications. We present four technical contributions. First, we develop and implement in Maude an executable specification of the operational semantics of a session-typed Ï-calculus by Vasconcelos. Second, we also develop an executable specification of its associated algorithmic type checking, and describe how both specifications can be integrated. Third, we show that our executable specification can be coupled with reachability and model checking tools in Maude to detect well-typed but deadlocked processes. Finally, we demonstrate the robustness of our approach by adapting it to a higher-order session Ï-calculus, in which exchanged values include names but also abstractions (functions from names to processes). All in all, our contributions define a promising new approach to the (semi)automated analysis of communication correctness in message-passing concurrency
The Frequency of Carbon Stars Among Extremely Metal-Poor Stars
We demonstrate that there are systematic scale errors in the [Fe/H] values
determined by the Hamburg/ESO Survey (and by inference by the HK Survey in the
past) for certain extremely metal poor highly C-enhanced giants. The
consequences of these scale errors are that a) the fraction of carbon stars at
extremely low metallicities has been overestimated in several papers in the
recent literature b) the number of extremely metal poor stars known is somewhat
lower than has been quoted in the recent literature c) the yield for extremely
metal poor stars by the HES Survey is somewhat lower than is stated in the
recent literature. A preliminary estimate for the frequency of Carbon stars
among the giants in the HES sample with -4 < [Fe/H] < -2.0 dex is 7.4 +-2.9%;
adding an estimate for the C-enhanced giants with [C/Fe] > 1.0 dex without
detectable C2 bands raises the fraction to 14 +-4$%.
We rely on the results of an extensive set of homogeneous detailed abundance
analyses of stars expected to have [Fe/H] < -3.0 dex selected from the HES to
establish these claims. We have found that the Fe-metallicity of the cooler
(Teff < 5200K) C-stars as derived from spectra taken with HIRES at Keck are a
factor of ~10 higher than those obtained via the algorithm used by the HES
project to analyze the moderate resolution follow-up spectra, which is
identical to that used until very recently by the HK Survey. This error in
Fe-abundance estimate for C-stars arises from a lowering of the emitted flux in
the continuum bandpasses of the KP (3933 A line of CaII) and particularly the
HP2 (Hdelta) indices used to estimate [Fe/H] due to absorption from strong
molecular bands.Comment: Accepted to the ApJL after a very lengthly duel with the 3
simultaneous referee
Conscious mobility for urban spaces: case studies review and indicator framework design
A lack of data collection on conscious mobility behaviors has been identified in current sustainable and smart mobility planning, development and implementation strategies. This leads to technocentric solutions that do not place people and their behavior at the center of new mobility solutions in urban centers around the globe. This paper introduces the concept of conscious mobility to link techno-economic analyses with user awareness on the impact of their travel decisions on other people, local urban infrastructure and the environment through systematic big data collection. A preliminary conscious mobility indicator framework is presented to leverage behavioral considerations to enhance urban-community mobility systems. Key factors for conscious mobility analysis have been derived from five case studies. The sample offers regional diversity (i.e., local, regional and the global urban contexts), as well as different goals in the transformation of conventional urban transport systems, from improving public transport efficiency and equipment electrification to mitigate pollution and climate risks, to focusing on equity, access and people safety. The case studies selected provide useful metrics on the adoption of cleaner, smarter, safer and more autonomous mobility technologies, along with novel people-centric program designs to build an initial set of conscious mobility indicators frameworks. The parameters were applied to the city of Monterrey, Nuevo Leon in Mexico focusing on the needs of the communities that work, study and live around the local urban campus of the Tecnologico de Monterreyâs Distrito Tec. This case study, served as an example of how conscious mobility indicators could be applied and customized to a community and region of interest. This paper introduces the first application of the conscious mobility framework for urban communitiesâ mobility system analysis. This more holistic assessment approach includes dimensions such as society and culture, infrastructure and urban spaces, technology, government, normativity, economy and politics, and the environment. The expectation is that the conscious mobility framework of analysis will become a useful tool for smarter and sustainable urban and mobility problem solving and decision making to enhance the quality of life all living in urban communities
Effect of a DC Electric field on the melting temperature, nucleation and ice growth rate of the TIP4P/ICE water model
Understanding the effect of electric fields on the thermal stability and phase transitions of water could have potential applications in the food industry, cryopreservation, and environmental science. In this work, we investigate the effect of a static electric field on the
melting temperature (Tm), ice nucleation and ice growth rate of two phases of ice, hexagonal ice (Ih) and ferroelectric cubic ice (Icf), for the TIP4P/ICE water model. By means of direct coexistence simulations, we establish that Tm of Ice Ih is shifted toward lower values, whereas Tm of Ice Icf grows, becoming the most stable ice phase for sufficiently largevalues of the applied electric field. We also investigate ice nucleation for both ice phases under an external electric field and find that, for a given supercooling with respect to Tm, while the field slows down the nucleation rate of ice Ih significantly, it barely affects that of ice Icf, due to the enhanced ability of water molecules to orient favorably along the direction of the field in the latter phase. In terms of absolute temperature, overall ice formation is promoted by the electric field because it increases the melting point of ice Icf. Finally, we show how the electric field slows down the crystal growth of Ice Ih and increases that of Ice Icf by a factor of about two
Pre-print -In review for publication in Water Resources Research Trends in Regional Evapotranspiration across the United States under the Complementary Relationship Hypothesis
Abstract The hypothesis of a complementary relationship in regional evapotranspiration allows for estimation of actual evapotranspiration on a regional scale by simple, physically based models that take into account feedbacks in land surface-atmosphere dynamics. A regional, seasonal Advection-Aridity model is used to create a spatially distributed, monthly time-series of actual evapotranspiration for a period of 27 years at a 5-km resolution over the conterminous United States. For the conterminous United States as a whole, a 4.3% increase in annual actual evapotranspiration over the period WY 1962WY -1988 was observed, a trend that was significant at the 90% confidence level according to the Mann-Kendall test. Trends in annual evapotranspiration are analyzed across the spatial scales of the continental United States, a Water Resources Region (WRR), a river basin of 16,000 km 2 , and an individual 5-km square cell. Reducing the spatial scale allowed for clearer identification of areas with significant trends. To establish a base-line for the study of climate change and/or variability, a methodology for rigorous examination of past trends in actual evapotranspiration is proposed, wherein such trends are broken down into the climatic components of actual evapotranspiration in the context of the complementary relationship, and no assumptions are made about the temporal stationarity of the net available energy. Trends in actual evapotranspiration can thus be determined to originate in either the energy budget or the water budget, or both
A comparison of the peers method and traditional methodologies, and risk behaviors in studies of the prevalence of drug consumption in a population of female, chilean students
Este estudio investiga el consumo de drogas y los comportamientos de riesgo de alumnas entre los 8Âș y 12Âș cursos en dos comunidades de la ciudad de Santiago, Chile. Empleando dos mĂ©todos para investigar el consumo, y basĂĄndonos en los estudios de poblaciones universitarias, hipotetizamos que los autoinformes de las alumnas sobre su consumo de drogas legales tenderĂĄn a ser consistentes con el uso real de dichas drogas, mientras que su consumo de drogas ilĂcitas serĂĄ susceptible y tenderĂĄn a infra-informar de ello cuando se evalĂșa a travĂ©s de medidas tradicionales de autoinforme. Para comparar los dos mĂ©todos, se diseñó un estudio transversal que compararĂa el consumo informado, primero empleando el mĂ©todo de pares, y despuĂ©s por medio del autoinforme tradicional, en un grupo de 350 alumnas. Los resultados muestran que los informes de las chicas sobre su consumo de drogas legales convergen empleando los dos mĂ©todos, mientras que, como se ha sugerido, infra-informaban sobre su consumo de drogas ilegales cuando se empleaban metodologĂas tradicionales.The present study investigates drug consumption and risk behaviors among female students between 8th and 12th grade in two communities in the city of Santiago, Chile. Based on studies of university populations, we hypothesize that the studentsâ reports of their consumption of licit drugs will tend to be consistent with their actual use of said drugs using two methods to investigate consumption, while their consumption of illicit drugs will be susceptible, and will tend to be under reported when evaluated through traditional self-report measures. In order to compare the two methods, a cross-sectional study was designed that would compare reported drug consumption, first using the peers method, and then by means of traditional self-report in a group of 350 students. The results show that womenâs reports of licit drug consumption converge using the two methods, while as earlier suggested, womenâs illicit drug consumption was found to be under reported when traditional methodologies were used
Energy-Based switches losses model for the optimization of PwrSoC buck converter
Current trends in automotive industry impose as main drivers the improvement of the efficiency and the miniaturization of the electronic systems. New technologies for passives enable the integration of inductor based power converter together with the load in a single chip. Due to the complexity of the system and various constraints, multi-variable optimization needs to be employed. This study presents an energy-based piece-wise linear model for switches losses estimation for 40 nm automotive approved semiconductor technology used for implementation of PwrSoC buck converter system. The model, based on discrete number of calculations performed with Spice simulations, is presented in detail in this study and it is validated experimentally
Microemulsions for colorectal cancer treatments: general considerations and formulation of methotrexate
[Abstract] Microemulsions combine the advantages of emulsions with those of nanocarriers, overcoming the stability problems of the former and providing facile scalable systems with compartments adequate for high drug loadings. Recently, microemulsions are gaining attention in the formulation of anticancer drugs not only for topical treatment, but also for systemic delivery as well as for the development of theranostic systems. The aim of this paper is two-fold. First, an updated review about general features, preparation, characterization and pharmaceutical applications, with a special focus on colorectal cancer, is provided. Second, a case study of formulation of methotrexate in microemulsions is presented. Various essential oils (menthol, trans-anethole, α-tocopherol) and surfactants (TPGS-l000, Maxemul 6112, Noigen RN-20) were investigated for the preparation of o/w microemulsions for the delivery of methotrexate, and the ability of methotrexate-loaded microemulsions to inhibit cancer cell growth was then evaluated. Disregarding the surfactants used, menthol and trans-anethole led to cytotoxic microemulsions, whereas α-tocopherol based-formulations induced cell proliferation. These findings highlight the role that the oily component may play in the efficacy and safety of the microemulsions.México. Consejo Nacional de Ciencia y Tecnologia; No. CB-2011/ 168472Ministerio de Economia y Competitividad; SAF2014-52632-RRed Gallega de Investigación sobre Cåncer Colorrectal; R2014/03
Does native Trypanosoma cruzi calreticulin mediate growth inhibition of a mammary tumor during infection?
IndexaciĂłn: Web of Science.Background: For several decades now an antagonism between Trypanosoma cruzi infection and tumor development has been detected. The molecular basis of this phenomenon remained basically unknown until our proposal that T. cruzi Calreticulin (TcCRT), an endoplasmic reticulum-resident chaperone, translocated-externalized by the parasite, may mediate at least an important part of this effect. Thus, recombinant TcCRT (rTcCRT) has important in vivo antiangiogenic and antitumor activities. However, the relevant question whether the in vivo antitumor effect of T. cruzi infection is indeed mediated by the native chaperone (nTcCRT), remains open. Herein, by using specific modified anti-rTcCRT antibodies (Abs), we have neutralized the antitumor activity of T. cruzi infection and extracts thereof, thus identifying nTcCRT as a valid mediator of this effect.
Methods: Polyclonal anti-rTcCRT F(ab')(2) Ab fragments were used to reverse the capacity of rTcCRT to inhibit EAhy926 endothelial cell (EC) proliferation, as detected by BrdU uptake. Using these F(ab')(2) fragments, we also challenged the capacity of nTcCRT, during T. cruzi infection, to inhibit the growth of an aggressive mammary adenocarcinoma cell line (TA3-MTXR) in mice. Moreover, we determined the capacity of anti-rTcCRT Abs to reverse the antitumor effect of an epimastigote extract (EE). Finally, the effects of these treatments on tumor histology were evaluated.
Results: The rTcCRT capacity to inhibit ECs proliferation was reversed by anti-rTcCRT F(ab')(2) Ab fragments, thus defining them as valid probes to interfere in vivo with this important TcCRT function. Consequently, during infection, these Ab fragments also reversed the in vivo experimental mammary tumor growth. Moreover, anti-rTcCRT Abs also neutralized the antitumor effect of an EE, again identifying the chaperone protein as an important mediator of this anti mammary tumor effect. Finally, as determined by conventional histological parameters, in infected animals and in those treated with EE, less invasive tumors were observed while, as expected, treatment with F(ab')(2) Ab fragments increased malignancy.
Conclusion: We have identified translocated/externalized nTcCRT as responsible for at least an important part of the anti mammary tumor effect of the chaperone observed during experimental infections with T. cruzi.http://bmccancer.biomedcentral.com/articles/10.1186/s12885-016-2764-
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