2,075 research outputs found
Is U(1) a Good Family Symmetry?
We analyze U(1) as a horizontal symmetry and its possibilities to explain
the known elementary-fermion masses. We find that only two candidates, in the
context of SU(3)SU(2)U(1)U(1)
nonsupersymmetric, are able to fit the experimental result mm.Comment: 10 pages, Accepted for publication in Z. Phys.
Total Synthesis of Mansouramycin A
In 2009 bioactive compounds from marine Streptomyces species was isolated which resulted in deriving four isoquinoline-quinone alkaloids known as Mansouramycins A-D. There have been reports that there are 36 non-small cancer cells against cytotoxicity in Mansouramycins A-C in lung cancer, breast cancer, melanoma, and prostate cancer cells. Reports that have conducted total syntheses were all specific to a single compound only Mansouramycin A and D. However, in precedent methods, to obtain the derivatives with different substituents are limited when the substituents are on the fused-pyridine ring. Thus, a develop a systematic synthetic methods of isoquinoline-quinones, which are to be able to obtain the natural Mansouramycins and their derivative by the usage of different amino acids via synthesis the aminoacetals
NanopartĂculas PolimĂ©ricas en DermocosmĂ©tica
IndexaciĂłn: Web of Science; Scielo.Recent advances in the fields of biomaterials and nanotechnology have allowed the development of advanced nanoparticles for biomedical applications. Despite a vast number of nanostructures such as liposomes, solidÂlipid nanocapsules, polymeric and hybrid lipidÂpolymer nanoparticles have been studied as carriers for drug delivery for different pathologies with remarkable promising results; the use of polymeric nanoparticles in dermocosmetic still has not been widely explored. The evolution of cosmetic into the care skin and dermatology represents novel technological challenges. Also, the increasing knowledge about normal skin physiology and advances in nanotechnology provide an attractive environment for the creation of innovative dermocosmetic formulations. In this work, we discuss the state of the art of polymeric nanoparticles formulated for dermocosmetics, its mechanisms of action, and diffusion into the skin.Los recientes avances en el campo de los biomateriales y la nanotecnologĂa han permitido el desarrollo de nanopartĂculas avanzadas para aplicaciones biomĂ©dicas. A pesar de que un gran nĂșmero de nanoestructuras tales como liposomas, nanocĂĄpsulas lĂpido-sĂłlidas, nanopartĂculas polimĂ©ricas y lĂpido-polĂmero hĂbridas han sido estudiadas como vehĂculos para la administraciĂłn de fĂĄrmacos en diferentes patologĂas con notables resultados prometedores, el uso de nanopartĂculas polimĂ©ricas en dermocosmĂ©tica todavĂa no ha sido ampliamente explorado. La evoluciĂłn de la cosmĂ©tica en el cuidado de la piel y la dermatologĂa nos enfrentan a nuevos retos tecnolĂłgicos. AdemĂĄs, el aumento de los conocimientos sobre la fisiologĂa de la piel normal y los avances en la nanotecnologĂa proporcionan un entorno atractivo para la creaciĂłn de formulaciones dermocosmĂ©ticas innovadoras. En este trabajo se discute el estado del arte de las nanopartĂculas polimĂ©ricas desarrolladas para dermocosmĂ©tica, sus mecanismos de acciĂłn y la difusiĂłn en la piel.http://ref.scielo.org/b68hz
Teacher Evaluation and Reliability: Additional Insights Gathered from Inter-rater Reliability Analyses
Using a newly-created teacher evaluation instrument, Inter-rater Reliability (IRR) analyses were conducted on four teacher videos as a means to establish instrument reliability. Raters included 42 principals and assistant principals in a southern US school district. The videos used spanned the teacher quality spectrum and the IRR findings across these levels varied. Key findings suggest that while the overall IRR coefficient may be adequate to assess the validity of a classroom observation instrument, the overall coefficient may be unstable across the various teacher performance levels. Findings also strongly suggest that raters are much more likely to agree when they see high-quality teaching when compared to levels of agreement regarding low-quality teaching
Vegetable Production and Pesticide Use in Ghana: Would GM Varieties Have an Impact at the Farm Level?
The objective of this study is to evaluate pesticide use as an important factor affecting potential adoption and farm level impact of genetically modified (GM) vegetable varieties in Ghana. Tomato is the most consumed vegetable and a food security crop. Cabbage is a vegetable of growing importance but limited cultivation and is produced in urban areas. Garden egg is a native African crop of wide consumption and importance for rural economies. Farm level information was collected in randomly selected sites in southern and central regions of Ghana. Partial budget analysis shows that investments in pesticides are rather low, especially for tomato and garden egg. Analysis of production using an abatement framework shows that insecticide amounts are significant in determining cabbage output levels only. Rate of returns of GM seeds however can still be high. GM varieties would need to show not only a high abatement rate and a high yield potential but mainly an affordable price, to reduce total costs and induce adoption.Farm, Genetically Modified, Ghana, Tomato, Agricultural and Food Policy, Consumer/Household Economics, Environmental Economics and Policy, Food Consumption/Nutrition/Food Safety, Food Security and Poverty, Health Economics and Policy, International Relations/Trade, Marketing, Productivity Analysis, Research and Development/Tech Change/Emerging Technologies,
Insecticide Use on Vegetables in Ghana: Would GM Seed Benefit Farmers?
Tomato, cabbage and garden egg (African eggplant, or Solanum Aethiopicum) are important crops for small-scale farmers and migrants in the rural and peri-urban areas of Ghana. Genetic modification (GM) has the potential to alleviate poverty through combating yield losses from pests and diseases in these crops, while reducing health risks from application of hazardous chemicals. This ex-ante study uses farm survey data to gauge the potential for adoption of genetically-engineered varieties, estimate the potential impact of adoption on farm profits, and highlight economic differences among the three crops. Farmer's expenditures on insecticides are below the economic optimum in all three crops, and the estimated function for damage abatement shows that insecticide amounts are significant determinants of cabbage yields only. Nonetheless, yield losses from the pests and diseases affect insecticide use. Stochastic budget analysis also indicates a higher rate of return to vegetable production with the use of resistant seeds relative to status quo, even considering the technology transfer fee for GM seeds. Non-insecticide users could accrue higher marginal benefits than current insecticide users. Comparing among vegetable crops with distinct economic characteristics provides a wider perspective on the potential impact of GM technology. Until now, GM eggplant is the only vegetable crop that has been analyzed in the peer-reviewed, applied economics literature. This is the first analysis that includes African eggplant.Crop Production/Industries, Research and Development/Tech Change/Emerging Technologies,
The Cost of Compliance with Biosafety Regulations in Indonesia and The Philippines
Resource /Energy Economics and Policy,
Dental caries in Mexican schoolchildren : a comparison of 1988?1989 and 1998?2001 surveys
Objectives: To compare two surveys across seven states for the prevalence of dental caries among Mexican schoolchildren. Study D esign: Analysis of two cross-sectional surveys: Schoolchildren from 6 to 10 years of age were examined in the 1988?1989 survey and 6- to 10-year-old and 12-year-old students were included in the 1998?2001 survey. The baseline data of seven states were available for analysis. Representative probability samples were conducted statewide in both surveys. The World Health Organization (WHO) method was used to obtain the dental caries index (dmft, DMFT). At present, additional and more recent epidemiological data representative statewide in Mexico are unavailable. Results: The participants were 9798 schoolchildren in the 1988?1989 survey and 16882 schoolchildren in the 1998?2001 survey. The prevalence of caries in children ages 6 to 10 years was 86,6% in the first survey and 65,5% in the second survey, showing a 24,4% reduction. The primary teeth index in the first survey was dmft = 3,86 (IC95% 3,68 4,04) and in permanent teeth, it was DMFT = 1,03 (IC95% 0,95 1,11). In the second survey, the comparable values were dmft = 2,36 (IC95% 2,20 2,52) and DMFT = 0,35 (IC95% 0,29 0,40), corresponding to a reduction of 38,89% and 66,02% in the primary and permanent dentition, respectively. Treatment needs remain high: In the second survey, as 92,75% of the index DMFT was conformed as decayed teeth. Conclusion: Overall, we detected a downward trend in the dental caries indices, particularly in the permanent dentition. The increase in the availability of fluoride likely contributed to the observed decline in dental carie
Vine Robots: Design, Teleoperation, and Deployment for Navigation and Exploration
A new class of continuum robots has recently been explored, characterized by
tip extension, significant length change, and directional control. Here, we
call this class of robots "vine robots," due to their similar behavior to
plants with the growth habit of trailing. Due to their growth-based movement,
vine robots are well suited for navigation and exploration in cluttered
environments, but until now, they have not been deployed outside the lab.
Portability of these robots and steerability at length scales relevant for
navigation are key to field applications. In addition, intuitive
human-in-the-loop teleoperation enables movement in unknown and dynamic
environments. We present a vine robot system that is teleoperated using a
custom designed flexible joystick and camera system, long enough for use in
navigation tasks, and portable for use in the field. We report on deployment of
this system in two scenarios: a soft robot navigation competition and
exploration of an archaeological site. The competition course required movement
over uneven terrain, past unstable obstacles, and through a small aperture. The
archaeological site required movement over rocks and through horizontal and
vertical turns. The robot tip successfully moved past the obstacles and through
the tunnels, demonstrating the capability of vine robots to achieve navigation
and exploration tasks in the field.Comment: IEEE Robotics and Automation Magazine, 2019. Video available at
https://youtu.be/9NtXUL69g_
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