805 research outputs found
Coefficient of performance at maximum figure of merit and its bounds for low-dissipation Carnot-like refrigerators
The figure of merit for refrigerators performing finite-time Carnot-like
cycles between two reservoirs at temperature and () is
optimized. It is found that the coefficient of performance at maximum figure of
merit is bounded between 0 and for the
low-dissipation refrigerators, where is the
Carnot coefficient of performance for reversible refrigerators. These bounds
can be reached for extremely asymmetric low-dissipation cases when the ratio
between the dissipation constants of the processes in contact with the cold and
hot reservoirs approaches to zero or infinity, respectively. The observed
coefficients of performance for real refrigerators are located in the region
between the lower and upper bounds, which is in good agreement with our
theoretical estimation.Comment: 5 journal pages, 3 figure
The effect of institutional distance on cross-border merger and acquisition time to completion: an empirical analysis of European Union deals
Cross-border merger and acquisitions (CBM&As) have extensively been used as a
favorite entry mode in foreign markets, rapidly providing resources, competencies and
local intelligence without risk of facing the liability of foreignness, or the burden of
starting a greenfield investment. Studies indicate that greater institutional distance
increases the costs of doing business in a foreign country, because it is associated with
greater uncertainty and non-familiarity with the local environment. Besides that, prolonged
duration of the M&A process has negative consequences for target and acquirer firms and
bear significant costs for both parties. However, until so far, the studies regarding the
effect of institutional distances on time to completion of a CBM&A deal are scarce. My
theoretical model speculates on the effect of institutional distances (Political, Economic,
Administrative and Cultural) in CBM&As time to completion. I further propose that
European Union membership, of both target and acquirer countries, moderates the effect of
institutional distances on CBM&As time to completion. The hypotheses are tested using a
sample of 2,110 CBM&A deals that occurred during 2011 in European Union. On one
hand, the results suggest that Political and Cultural distance have a positive effect on the
time hiatus between announcement and completion of a CBM&A deal. On the other hand,
the results suggest that European Union membership does moderate the effect of Economic and Administrative distance in CBM&A time to completion
Knowledge politics and new converging technologies: a social epistemological perspective
The “new converging technologies” refers to the prospect of advancing the human condition by the integrated study and application of nanotechnology, biotechnology, information technology and the cognitive sciences - or “NBIC”. In recent years, it has loomed large, albeit with somewhat different emphases, in national science policy agendas throughout the world. This article considers the political and intellectual sources - both historical and contemporary - of the converging technologies agenda. Underlying it is a fluid conception of humanity that is captured by the ethically challenging notion of “enhancing evolution”
Pumped heat energy storage with liquid media: Thermodynamic assessment by a transcritical Rankine-like model
[EN]A pumped heat energy storage (PHES) system based on a Rankine cycle for supercritical working fluids, such
as carbon dioxide and ammonia, accounting for the irreversible latent and sensible heat transfers between
the working fluid and the storage liquid medium, as water or thermal oil, is analyzed. The model also
includes several parameters such as pressure losses, heat exchanger efficiencies, and isentropic efficiencies of
the compressor, pump, and expansion devices (such as turbines and valves), that take into account the main
internal and external losses and heat leak to the environment. The model allows for the calculation of specific
energy, the heat pump performance coefficient, heat engine efficiency, and overall round-trip efficiency, as well
as the temperatures of the working fluid and reservoirs. A zero-dimensional model is also used to determine
the time dependence of heat leak in the tanks. The main results show that this technology could achieve
round trip efficiency values in the order of 50–70%. Irreversibilities in compression and expansion appears
as the most influential energy losses factor. The time effect of the ambient conditions on the tanks has been
analyzed for a wet subtropical climate but it seems that the ambient conditions have no major influence on the
performance of the system. In addition, explicit numerical results and temperature–entropy plots are presented
for two representative systems as carbon dioxide-water and ammonia-thermal oil to take into account the main
values in an operating condition
How interdisciplinary is nanotechnology?
Facilitating cross-disciplinary research has attracted much attention in recent years, with special concerns in nanoscience and nanotechnology. Although policy discourse has emphasized that nanotechnology is substantively integrative, some analysts have countered that it is really a loose amalgam of relatively traditional pockets of physics, chemistry, and other disciplines that interrelate only weakly. We are developing empirical measures to gauge and visualize the extent and nature of interdisciplinary interchange. Such results speak to research organization, funding, and mechanisms to bolster knowledge transfer. In this study, we address the nature of cross-disciplinary linkages using “science overlay maps” of articles, and their references, that have been categorized into subject categories. We find signs that the rate of increase in nano research is slowing, and that its composition is changing (for one, increasing chemistry-related activity). Our results suggest that nanotechnology research encompasses multiple disciplines that draw knowledge from disciplinarily diverse knowledge sources. Nano research is highly, and increasingly, integrative—but so is much of science these days. Tabulating and mapping nano research activity show a dominant core in materials sciences, broadly defined. Additional analyses and maps show that nano research draws extensively upon knowledge presented in other areas; it is not constricted within narrow silos
Pharmacogenetics, tobacco, alcohol and its effect on the risk development cancer
Indexación: Scopus; Scielo.Cancer is the second leading cause of death in the world, causing 8.8 million deaths in 2015 according to the World Health Organization (WHO). Risk factors for cancer include smoking and alcohol consumption. In Chile, 33.6% of the population and 21.2% of young people smokes. Alcohol consumption in the Chilean population is 74.5% and 12.2% in young people. Among the physiological factors that influence the development of cancer, the genetic factor plays a relevant role. It has been shown that the presence of genetic polymorphisms that alter the ability of the body to eliminate contaminants increase the risk of developing cancer. The same applies to polymorphisms that prevent DNA repair due to damage caused by environmental pollutants such as cigarette smoke. The objective of this review is to analyze the state of the art of the relationship between pharmacogenetics, smoking, and alcohol consumption as risk factors for the development of cancer. In conclusion, the results suggest that the presence of polymorphisms that alter the function of biotransformation enzymes phase I (CYP1A1, CYP1E1) and phase II (GST), as well as polymorphisms in DNA repair enzymes (ERCC1 / ERCC2), increase the risk of cancer induced by smoking and alcohol consumption. This association is important considering that smoking and drinking alcohol are highly prevalent among the Chilean population. © 2018, Sociedad Chilena de Pediatria. All rights reserved.Cancer is the second leading cause of death in the world, causing 8.8 million deaths in 2015 according to the World Health Organization (WHO). Risk factors for cancer include smoking and alcohol con sumption. In Chile, 33.6% of the population and 21.2% of young people smokes. Alcohol consump tion in the Chilean population is 74.5% and 12.2% in young people. Among the physiological factors that influence the development of cancer, the genetic factor plays a relevant role. It has been shown that the presence of genetic polymorphisms that alter the ability of the body to eliminate contami nants increase the risk of developing cancer. The same applies to polymorphisms that prevent DNA repair due to damage caused by environmental pollutants such as cigarette smoke. The objective of this review is to analyze the state of the art of the relationship between pharmacogenetics, smoking, and alcohol consumption as risk factors for the development of cancer. In conclusion, the results suggest that the presence of polymorphisms that alter the function of biotransformation enzymes phase I (CYP1A1, CYP1E1) and phase II (GST), as well as polymorphisms in DNA repair enzymes (ERCC1 / ERCC2), increase the risk of cancer induced by smoking and alcohol consumption. This association is important considering that smoking and drinking alcohol are highly prevalent among the Chilean population.https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0370-41062018005000709&lng=en&nrm=iso&tlng=e
Nano Mapper: an Internet knowledge mapping system for nanotechnology development
Nanotechnology research has experienced rapid growth in recent years. Advances in information technology enable efficient investigation of publications, their contents, and relationships for large sets of nanotechnology-related documents in order to assess the status of the field. This paper presents the development of a new knowledge mapping system, called Nano Mapper (http://nanomapper.eller.arizona.edu), which integrates the analysis of nanotechnology patents and research grants into a Web-based platform. The Nano Mapper system currently contains nanotechnology-related patents for 1976–2006 from the United States Patent and Trademark Office (USPTO), European Patent Office (EPO), and Japan Patent Office (JPO), as well as grant documents from the U.S. National Science Foundation (NSF) for the same time period. The system provides complex search functionalities, and makes available a set of analysis and visualization tools (statistics, trend graphs, citation networks, and content maps) that can be applied to different levels of analytical units (countries, institutions, technical fields) and for different time intervals. The paper shows important nanotechnology patenting activities at USPTO for 2005–2006 identified through the Nano Mapper system
Developing nanotechnology in Latin America
This article investigates the development of nanotechnology in Latin America with a particular focus on Argentina, Brazil, Chile, and Uruguay. Based on data for nanotechnology research publications and patents and suggesting a framework for analyzing the development of R&D networks, we identify three potential strategies of nanotechnology research collaboration. Then, we seek to identify the balance of emphasis upon each of the three strategies by mapping the current research profile of those four countries. In general, we find that they are implementing policies and programs to develop nanotechnologies but differ in their collaboration strategies, institutional involvement, and level of development. On the other hand, we find that they coincide in having a modest industry participation in research and a low level of commercialization of nanotechnologies
Grand Challenges in Global Health: The Ethical, Social and Cultural Program
The Grand Challenges initiative has 44 projects worldwide aimed at addressing diseases of the poor. What are the ethical, social, and cultural issues that the initiative faces
Trends for nanotechnology development in China, Russia, and India
China, Russia, and India are playing an increasingly important role in global nanotechnology research and development (R&D). This paper comparatively inspects the paper and patent publications by these three countries in the Thomson Science Citation Index Expanded (SCI) database and United States Patent and Trademark Office (USPTO) database (1976–2007). Bibliographic, content map, and citation network analyses are used to evaluate country productivity, dominant research topics, and knowledge diffusion patterns. Significant and consistent growth in nanotechnology papers are noted in the three countries. Between 2000 and 2007, the average annual growth rate was 31.43% in China, 11.88% in Russia, and 33.51% in India. During the same time, the growth patterns were less consistent in patent publications: the corresponding average rates are 31.13, 10.41, and 5.96%. The three countries’ paper impact measured by the average number of citations has been lower than the world average. However, from 2000 to 2007, it experienced rapid increases of about 12.8 times in China, 8 times in India, and 1.6 times in Russia. The Chinese Academy of Sciences (CAS), the Russian Academy of Sciences (RAS), and the Indian Institutes of Technology (IIT) were the most productive institutions in paper publication, with 12,334, 6,773, and 1,831 papers, respectively. The three countries emphasized some common research topics such as “Quantum dots,” “Carbon nanotubes,” “Atomic force microscopy,” and “Scanning electron microscopy,” while Russia and India reported more research on nano-devices as compared with China. CAS, RAS, and IIT played key roles in the respective domestic knowledge diffusion
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