Relativistic free-particle quantization on the light-front: New aspects

We use the light-front machinery to study the behavior of a relativistic free particle and obtain the quantum commutation relations from the classical Poisson brackets. We argue that the usual projection onto the light-front coordinates for these from the covariant commutation ralations does not reproduce the expected results.Comment: To appear in the proceedings "IX Hadron Physics and VII Relativistic Aspects of Nuclear Physics: A Joint Meeting on QCD and QGP, Hadron Physics-RANP,2004,Angra dos Reis, Rio de Janeiro,Brazi

Surprises in the relativistic free-particle quantization on the light-front

We use the light front ``machinery'' to study the behavior of a relativistic free particle and obtain the quantum commutation relations from the classical Poisson brackets. We argue that their usual projection onto the light-front coordinates from the covariant commutation relations show that there is an inconsistency in the expected correlation between canonically conjugate variables ``time'' and ``energy''. Moreover we show that this incompatibility originates from the very definition of the Poisson brackets that is employed and present a simple remedy to this problem and envisages a profound physical implication on the whole process of quantization.Comment: 13 page

Psoriasis and Cardiovascular Disease

A psoríase é uma doença inflamatória sistémica crónica, frequente, associada a várias comorbilidades, destacando-se a obesidade, a hipertensão arterial, a diabetes, a dislipidemia e síndrome metabólico. Adicionalmente associa-se também a aumento do risco de doença cardiovascular – enfarte agudo do miocárdio e acidente vascular cerebral. A inflamação sistémica crónica presente na psoríase tem sido sugerida como um factor de risco independente para estas comorbilidades e para o aparecimento de aterosclerose precoce. Esta revisão das várias comorbilidades cardio-metabólicas e do risco de doença cardiovascular associado à psoríase tem como objectivopromover o conhecimento e alertar os clínicos para a necessidade de rastreio, monitorização e tratamento dos factores de risco de doença cardiovascular nestes doentes

The changing Chinese community in London: new migration, new needs.

London’s Chinese population in London is one of the most rapidly growing of any national group and is becoming increasingly diverse as new forms of migration develop and people arrive from regions of China which have previously seen little emigration. These developments are a product of political and economic changes in both China and in Britain. The ending of restrictions on travel within China and its growing participation in the global economy have opened up new opportunities for internal and international migration. These new migrants include the most privileged - students, the highly skilled with established jobs in London - as well as those for whom China’s transformation to a market economy has meant dispossession and loss of livelihood. Many have been forced to emigrate for survival, often leaving family in China. Britain, with other European countries, has become increasingly dependent on migrant labour but immigration policies are increasingly selective, welcoming those with recognised skills while restricting entry to those deemed unskilled. Many of the new thus migrants find themselves forced to rely on ‘agents’ to enter the country and their insecure status means they have limited rights once they have arrived and are vulnerable to exploitation. The deaths of 20 Chinese cockle pickers in Morecambe Bay in 2004 drew attention to the ‘hidden’ population of new Chinese migrants. Many new migrants prosper and are able to take advantage of the opportunities which migration brings, but others, especially those with insecure legal and economic status, may struggle, often over a protracted period, to gain a foothold in British society. They may speak little English, have limited knowledge of British society and are poorly prepared to settle and find adequate work. They need support in order to access services, but many have little information about how to go about this and limited social networks to help them. Most of the established Chinese population in London migrated to Britain from Hong Kong and speak Cantonese, unlike the predominantly Mandarin-speaking new migrants. They have established a range of community, business and cultural organisations but these mainly cater for earlier generations. Some have struggled to respond to the new needs which these new migrants bring, but they often lack the necessary knowledge, language and resources. This report is based on research which focused on the experiences of this new population and ways in which service providers could support them in order to promote their inclusion. Although we focus on new migrants, we acknowledge that there is widespread poverty, exclusion and isolation among older generations of Chinese people, particularly as they reach retirement age. The research included all those identifying their ethnic origin as Chinese, including people from Hong Kong, Taiwan, Thailand and Vietnam. The majority of participants, however, came from mainland China. The study was based in London which has the largest and most diverse Chinese population in Britain and many Chinese organisations. We hope, however, that its findings and recommendations will also be relevant to the Chinese population across Britain. The research was carried out by researchers based at Middlesex University and working with Chinese community organisations in London. We are grateful to the Big Lottery Fund for their financial support and to the School of Health and Social Science at Middlesex University whose contribution ensured that the project was completed. We also wish to thank the informants from Chinese community organisations and the individuals interviewed for the research who have contributed generously with their time and ideas

A novel antibody-like material for breast cancer antigen CA15-3, used to track breast cancer by potentiometric transduction

This work presents the development of a low cost sensor device for the diagnosis of breast cancer in point-of-care, made with new synthetic biomimetic materials inside plasticized poly(vinyl chloride), PVC, membranes, for subsequent potentiometric detection. This concept was applied to target a conventional biomarker in breast cancer: Breast Cancer Antigen (CA15-3). The new biomimetic material was obtained by molecularly-imprinted technology. In this, a plastic antibody was obtained by polymerizing around the biomarker that acted as an obstacle to the growth of the polymeric matrix. The imprinted polymer was specifically synthetized by electropolymerization on an FTO conductive glass, by using cyclic voltammetry, including 40 cycles within -0.2 and 1.0 V. The reaction used for the polymerization included monomer (pyrrol, 5.0×10-3 mol/L) and protein (CA15-3, 100U/mL), all prepared in phosphate buffer saline (PBS), with a pH of 7.2 and 1% of ethylene glycol. The biomarker was removed from the imprinted sites by proteolytic action of proteinase K. The biomimetic material was employed in the construction of potentiometric sensors and tested with regard to its affinity and selectivity for binding CA15-3, by checking the analytical performance of the obtained electrodes. For this purpose, the biomimetic material was dispersed in plasticized PVC membranes, including or not a lipophilic ionic additive, and applied on a solid conductive support of graphite. The analytical behaviour was evaluated in buffer and in synthetic serum, with regard to linear range, limit of detection, repeatability, and reproducibility. This antibody-like material was tested in synthetic serum, and good results were obtained. The best devices were able to detect 5 times less CA15-3 than that required in clinical use. Selectivity assays were also performed, showing that the various serum components did not interfere with this biomarker. Overall, the potentiometric-based methods showed several advantages compared to other methods reported in the literature. The analytical process was simple, providing fast responses for a reduced amount of analyte, with low cost and feasible miniaturization. It also allowed the detection of a wide range of concentrations, diminishing the required efforts in previous sample pre-treating stages

Estimated Financial Performance of Exotic and Indigenous Tree Species in Smallholder Plantations in Leyte Province

This paper examines the need for estimates of financial performance of individual tree species for promoting smallholder forestry on Leyte Island in the Philippines, and presents some initial estimates of net present value and internal rate of return for smallholder plantings of indigenous and traditionally grown (exotic) tree species. Levels of profitability are found to be marginal for commercial production, particularly for native species. Data deficiencies are noted, and improved estimates of tree growth rates and rotation lengths in particular are needed to improve predictions of financial performance of smallholder forestry

Low-lying optical phonon modes in the filled skutterudite CeRu4Sb12

The phonon dynamics of filled skutterudite CeRu4Sb12 have been studied at room temperature by inelastic neutron scattering. Optical phonons associated with a large vibration of Ce atoms are observed at a relatively low energy of E = 6 meV, and show anticrossing behavior with acoustic phonons. We propose that the origin of the low lattice thermal conductivity in filled skutterudites can be attributed to intensive Umklapp scattering originating from low-lying optical phonons. By an analysis based on a Born-von Karman force model, the longitudinal force constants of the nearest Ce-Sb and Ce-Ru pairs are estimated to be 0.025 mdyn/A, while that of the nearest Ru-Sb pair is estimated to be 1.4 mdyn/A, indicating that the Ce atoms are bound very weakly to the surrounding rigid RuSb6-octahedron cages.Comment: 4pages, 5 figures, J. Phys. Soc. Jpn. (2006) in pres