4,943 research outputs found
Polarization singularities in the clear sky
No full textIdeas from singularity theory provide a simple account of the pattern of polarization directions in daylight. The singularities (two near the Sun and two near the anti-Sun) are points in the sky where the polarization line pattern has index +1/2 and the intensity of polarization is zero. The singularities are caused by multiple scattering that splits into two each of the unstable index +1 singularities at the Sun and anti-Sun, which occur in the single-dipole scattering (Rayleigh) theory. The polarization lines are contours of an elliptic integral. For the intensity of polarization (unnormalized degree), it is necessary to incorporate the strong depolarizing effect of multiple scattering near the horizon. Singularity theory is compared with new digital images of sky polarization, and gives an excellent description of the pattern of polarization directions. For the intensity of polarization, the theory can reproduce not only the zeros but also subtle variations in the polarization maxima
Antiviral potential of cathelicidins
No full textThe global burden of morbidity and mortality arising from viral infections is high; however, the development of effective therapeutics has been slow. As our understanding of innate immunity has expanded over recent years, knowledge of natural host defenses against viral infections has started to offer potential for novel therapeutic strategies. An area of current research interest is in understanding the roles played by naturally occurring cationic host defense peptides, such as the cathelicidins, in these innate antiviral host defenses across different species. This research also has the potential to inform the design of novel synthetic antiviral peptide analogs and/or provide rationale for therapies aimed at boosting the natural production of these peptides. In this review, we will discuss our knowledge of the antiviral activities of cathelicidins, an important family of cationic host defense peptides, and consider the implications for novel antiviral therapeutic approaches
The strategic symbiosis between us Asian policy and Taiwanese nationalism
No full textThis thesis explores the influence of us Asian policy on the evolution of Taiwanese nationalism and the role of Taiwanese nationalism in America's Asian policy. The study consists of five parts. The first part (1895-1950) introduces the source of Taiwanese nationalism and America's strategic scheme on Taiwan before 1945, and explores American options after the germination of Taiwanese nationalism. America's intention to separate Taiwan from the mainland so as to deny the island to Chinese Communists late 1948 helped preserve inchoate Taiwanese nationalism. The second part (1950-1970) examines how America simultaneously exploited the Chinese Nationalist regime's anti-communism and facilitated the growth of Taiwanese nationalism in the bipolarized Cold-War era. The Truman administration's separatist intention after the Korean War, US aid and American scholars' Taiwan independence theories had significant implications for the evolution of Taiwanese nationalism. The third part (1970-1989) examines how America reconciled US-PRC rapprochement with its promotion of Taiwanese nationalism. Taiwan's democratisation evolved in the context of US political, economic and military intervention. During the transition to democratisation, secessionists turned political opposition movement into nation-building revolution. The fourth part (1989-2000) examines how US conservatives and Taiwanese nationalists jointly promoted Taiwanization. The dynamics of democratisation, native president Lee Teng-hui's domination of political agenda, the ambience of US-Taiwan strategic realignment and the maturity of political nationalism together facilitated Taiwanization. The fifth part (2000֊present) explores how America and Taiwan establish a strategic symbiosis for US-China strategic competition. The 9/11 Incident has little influence on the course of strategic symbiosis. The consolidation of Taiwan identity obliged thepan-blue camp to identify with Taiwan, promote political nationalism and deviate from their pro-unification ideology. The increased antagonism between Taiwanese nationalism and Chinese nationalism ossifies the symbiotic partnership between USAsian policy and Taiwanese nationalism and hinders China's rise to regional hegemonyand global superpower
Ultra-short echo time cardiovascular magnetic resonance of atherosclerotic carotid plaque
No full textAbstract Background Multi-contrast weighted cardiovascular magnetic resonance (CMR) allows detailed plaque characterisation and assessment of plaque vulnerability. The aim of this preliminary study was to show the potential of Ultra-short Echo Time (UTE) subtraction MR in detecting calcification. Methods 14 ex-vivo human carotid arteries were scanned using CMR and CT, prior to histological slide preparation. Two images were acquired using a double-echo 3D UTE pulse, one with a long TE and the second with an ultra-short TE, with the same TR. An UTE subtraction (ΔUTE) image containing only ultra-short T2 (and T2*) signals was obtained by post-processing subtraction of the 2 UTE images. The ΔUTE image was compared to the conventional 3D T1-weighted sequence and CT scan of the carotid arteries. Results In atheromatous carotid arteries, there was a 71% agreement between the high signal intensity areas on ΔUTE images and CT scan. The same areas were represented as low signal intensity on T1W and areas of void on histology, indicating focal calcification. However, in 15% of all the scans there were some incongruent regions of high intensity on ΔUTE that did not correspond with a high intensity signal on CT, and histology confirmed the absence of calcification. Conclusions We have demonstrated that the UTE sequence has potential to identify calcified plaque. Further work is needed to fully understand the UTE findings.</p
Rapid hydrolysis of RNA with a CU-II complex
No full textPT: J; CR: ANDERSON B, 1977, J AM CHEM SOC, V99, P2652 BARBIER B, 1992, J AM CHEM SOC, V114, P3511 BASHKIN JK, 1994, J AM CHEM SOC, V116, P5981 BRESLOW R, 1986, J AM CHEM SOC, V108, P2655 BRESLOW R, 1989, P NATL ACAD SCI USA, V86, P1746 BRESLOW R, 1991, P NATL ACAD SCI USA, V88, P4080 CONNOLLY JA, 1994, INORG CHEM, V33, P665 GOBEL MW, 1992, ANGEW CHEM INT EDIT, V31, P207 GOBEL MW, 1992, ANGEW CHEM, V104, P217 GUSTAFSON RL, 1959, J AM CHEM SOC, V81, P525 HENDRY P, 1990, INORG CHEM, V29, P92 JUBIAN V, 1992, J AM CHEM SOC, V114, P1120 KOMIYAMA M, 1992, J CHEM SOC CHEM 0415, P640 MAGDA D, 1994, J AM CHEM SOC, V116, P7439 MATSUMOTO Y, 1990, J CHEM SOC CHEM COMM, P1050 MORROW JR, 1992, J AM CHEM SOC, V114, P1903 SCHNEIDER HJ, 1993, ANGEW CHEM INT EDIT, V32, P1716 SCHNEIDER HJ, 1993, ANGEW CHEM, V105, P1773 SMITH J, 1993, J AM CHEM SOC, V115, P362 STERN MK, 1990, J AM CHEM SOC, V112, P5357 SUMAOKA J, 1994, J CHEM SOC CHEM COMM, P1755 TAKASAKI BK, 1993, J AM CHEM SOC, V115, P9337 TAKASAKI BK, 1994, J AM CHEM SOC, V116, P1121 WAHNON D, 1994, J CHEM SOC CHEM COMM, P1441 WALL M, 1993, ANGEW CHEM INT EDIT, V32, P1633 WALL M, 1993, ANGEW CHEM, V105, P1696; NR: 26; TC: 82; J9: ANGEW CHEM INT ED; PG: 3; GA: QM404Source type: Electronic(1
Recent advances in minimally invasive colorectal cancer surgery
No full textLaparoscopy has improved surgical treatment of various diseases due to its limited surgical trauma and has developed as an interesting therapeutic alternative for the resection of colorectal cancer. Despite numerous clinical advantages (faster recovery, less pain, fewer wound and systemic complications, faster return to work) the laparoscopic approach to colorectal cancer therapy has also resulted in unusual complications, i.e. ureteral and bladder injury which are rarely observed with open laparotomy. Moreover, pneumothorax, cardiac arrhythmia, impaired venous return, venous thrombosis as well as peripheral nerve injury have been associated with the increased intraabdominal pressure as well as patient's positioning during surgery. Furthermore, undetected small bowel injury caused by the grasping or cauterizing instruments may occur with laparoscopic surgery. In contrast to procedures performed for nonmalignant conditions, the benefits of laparoscopic resection of colorectal cancer must be weighed against the potential for poorer long-term outcomes of cancer patients that still has not been completely ruled out. In laparoscopic colorectal cancer surgery, several important cancer control issues still are being evaluated, i.e. the extent of lymph node dissection, tumor implantation at port sites, adequacy of intraperitoneal staging as well as the distance between tumor site and resection margins. For the time being it can be assumed that there is no significant difference in lymph node harvest between laparoscopic and open colorectal cancer surgery if oncological principles of resection are followed. As far as the issue of port site recurrence is concerned, it appears to be less prevalent than first thought (range 0-2.5%), and the incidence apparently corresponds with wound recurrence rates observed after open procedures. Short-term (3-5 years) survival rates have been published by a number of investigators, and survival rates after laparoscopic surgery appears to compare well with data collected after conventional surgery for colorectal cancer. However, long-term results of prospective randomized trials are not available. The data published so far indicate that the oncological results of laparoscopic surgery compare well with the results of the conventional open approach. Nonetheless, the limited information available from prospective studies leads us to propose that minimally invasive surgery for colorectal cancer surgery should only be performed within prospective trials
Metabolic profiling and population screening of analgesic usage in nuclear magnetic resonance spectroscopy-based large-scale epidemiologic studies
No full textThe application of a 1H nuclear magnetic resonance (NMR) spectroscopy-based screening method for determining the use of two widely available analgesics (acetaminophen and ibuprofen) in epidemiologic studies has been investigated. We used samples and data from the cross-sectional INTERMAP Study involving participants from Japan (n = 1145), China (n = 839), U.K. (n = 501), and the U.S. (n = 2195). An orthogonal projection to latent structures discriminant analysis (OPLS-DA) algorithm with an incorporated Monte Carlo resampling function was applied to the NMR data set to determine which spectra contained analgesic metabolites. OPLS-DA preprocessing parameters (normalization, bin width, scaling, and input parameters) were assessed systematically to identify an optimal acetaminophen prediction model. Subsets of INTERMAP spectra were examined to verify and validate the presence/absence of acetaminophen/ibuprofen based on known chemical shift and coupling patterns. The optimized and validated acetaminophen model correctly predicted 98.2%, and the ibuprofen model correctly predicted 99.0% of the urine specimens containing these drug metabolites. The acetaminophen and ibuprofen models were subsequently used to predict the presence/absence of these drug metabolites for the remaining INTERMAP specimens. The acetaminophen model identified 415 out of 8436 spectra as containing acetaminophen metabolite signals while the ibuprofen model identified 245 out of 8604 spectra as containing ibuprofen metabolite signals from the global data set after excluding samples used to construct the prediction models. The NMR-based metabolic screening strategy provides a new objective approach for evaluation of self-reported medication data and is extendable to other aspects of population xenometabolome profiling
The tobacco industry in South Korea since market liberalisation : implications for strengthening tobacco control
No full textThis research analyses transnational tobacco companies' (TTCs)
broader strategies for market access and demand creation through
understanding market liberalisation in South Korea's tobacco industry from the
late 1980s in order to inform the strengthening of tobacco control policies
within the country and other emerging markets.
The research is mainly based on internal tobacco industry documents,
made publicly available through litigation. Detailed analysis of industry
documents related to South Korea has not been undertaken to date. Semistructured
interviews and additional primary and secondary sources served as
important supplementary data sources.
The key finding of this research is that the market access strategies of
TTCs, including direct and indirect lobbying on trade policies, were a response
to South Korea's export-oriented economic development model and its
negative attitude towards foreign investment. This was undertaken within the
context of the transformation of the world trading system from the 1980s which
created pressure on the country to open its market. After liberalisation, various
aggressive marketing tactics to create demand for foreign brands were used by
TTCs. The competition this engendered played a key role in the
transformation of the Korean tobacco monopoly into a private, competitive
business which emulated and refined the tactics used by TTCs. This, in turn,
increased the extent and intensity of the aggressive marketing of tobacco
products in Korea overall. Total volume of cigarette sales increased 25% as a
result, making Korea the 8th largest tobacco market in the world by 1992,
whilst smoking prevalence increased among young adults and females.
The research concludes that a fuller understanding of TTCs' strategies
for global expansion can be derived by locating them within the economic
development models of specific countries or regions. Such analysis, in turn,
offers important lessons for strengthening global tobacco control. Of
foremost importance is the need for emerging markets to appropriately balance
economic and public health policies when considering liberalisation. The
South Korean experience also demonstrates that comprehensive tobacco
control policies, as set out by the Framework Convention on Tobacco Control,
must be implemented prior to any market liberalisation and strictly enforced
within a competitive market environment
Poor quality drugs: grand challenges in high throughput detection, countrywide sampling, and forensics in developing countries.
No full textThroughout history, poor quality medicines have been a persistent problem, with periodical crises in the supply of antimicrobials, such as fake cinchona bark in the 1600s and fake quinine in the 1800s. Regrettably, this problem seems to have grown in the last decade, especially afflicting unsuspecting patients and those seeking medicines via on-line pharmacies. Here we discuss some of the challenges related to the fight against poor quality drugs, and counterfeits in particular, with an emphasis on the analytical tools available, their relative performance, and the necessary workflows needed for distinguishing between genuine, substandard, degraded and counterfeit medicines
Identification of a novel type of spacer element required for imprinting in fission yeast
No full textAsymmetrical segregation of differentiated sister chromatids is thought to be important for cellular differentiation in higher
eukaryotes. Similarly, in fission yeast, cellular differentiation involves the asymmetrical segregation of a chromosomal
imprint. This imprint has been shown to consist of two ribonucleotides that are incorporated into the DNA during laggingstrand
synthesis in response to a replication pause, but the underlying mechanism remains unknown. Here we present key
novel discoveries important for unravelling this process. Our data show that cis-acting sequences within the mat1 cassette
mediate pausing of replication forks at the proximity of the imprinting site, and the results suggest that this pause dictates
specific priming at the position of imprinting in a sequence-independent manner. Also, we identify a novel type of cis-acting
spacer region important for the imprinting process that affects where subsequent primers are put down after the
replication fork is released from the pause. Thus, our data suggest that the imprint is formed by ligation of a not-fullyprocessed
Okazaki fragment to the subsequent fragment. The presented work addresses how differentiated sister
chromatids are established during DNA replication through the involvement of replication barriers
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