5,143 research outputs found
Continuous Spin Representations from Group Contraction
We consider how the continuous spin representation (CSR) of the Poincare
group in four dimensions can be generated by dimensional reduction. The
analysis uses the front-form little group in five dimensions, which must yield
the Euclidean group E(2), the little group of the CSR. We consider two cases,
one is the single spin massless representation of the Poincare group in five
dimensions, the other is the infinite component Majorana equation, which
describes an infinite tower of massive states in five dimensions. In the first
case, the double singular limit j,R go to infinity, with j/R fixed, where R is
the Kaluza-Klein radius of the fifth dimension, and j is the spin of the
particle in five dimensions, yields the CSR in four dimensions. It amounts to
the Inonu-Wigner contraction, with the inverse K-K radius as contraction
parameter. In the second case, the CSR appears only by taking a triple singular
limit, where an internal coordinate of the Majorana theory goes to infinity,
while leaving its ratio to the KK radius fixed.Comment: 22 pages; some typos correcte
China: from consumer goods manufacturer to innovation leader ?
In this study, we will first explore the definition of innovation and reverse innovation. Innovation is on every lip now and it is important to explore and define clearly their exact meaning for this study. Reverse innovation is one of the most important concepts in a study about China. As Roger L. Martin, dean of the Rotman School of Management, University of Toronto said, âWater may not flow uphill but innovation does!â and it is something we have to examine since it might be the key for the Western countriesâ companies to stay competitive against the Chinese ones. This study will then examine the current state of innovation in the Western countries and in China to dress a rapid image of where innovation stands now and whether it is shifting from Western countries to China. We will also dress an overview of the current economic situation in China, the worldâs second largest economy rising strongly for many years. China is having a worrying indebtedness situation caused by a huge investment in construction to counter the decline of GDP caused by the 2008 crisis in the Western countries. We will see how China wants to solve that by investing in innovation, helped by many factors such as the good market opportunities, the strong capital availability and a wish from the government to change its economy from production and investment driven economy to an innovation driven economy by promoting technological innovation. Finally, with the example of the smartphone industry, we will analyze in what extent China effectively raised its investment in innovation and how its smartphone production and exports are booming. We will conclude by dressing two possible scenarios for its future that could be a crisis such as the one the Western countries knew in 2008, or to become the worldâs innovation leader
Deserving citizenship? Exploring migrants' experiences of the âcitizenship testâ process in the United Kingdom
Since the early 2000s several European countries have introduced language and citizenship tests as new requirements for access to long-term residence or naturalization. The content of citizenship tests has been often presented as exclusionary in nature, in particular as it is based on the idea that access to citizenship has to be 'deserved'. In this paper, we aim to explore the citizenship tests 'from below', through the focus on the experience of migrants who prepare and take the 'Life in the UK' test, and with particular reference to how they relate to the idea of 'deservingness'. Through a set of in-depth interviews with migrants in two different cities (Leicester and London), we show that many of them use narratives in which they distinguish between the 'deserving citizens' and the 'undeserving Others' when they reflect upon their experience of becoming citizens. In so doing, they negotiate new hierarchies of inclusion into and exclusion from citizenship, which reflect broader neo-liberal and ethos-based conceptions of citizenship
Continuous Spin Representations of the Poincar\'e and Super-Poincar\'e Groups
We construct Wigner's continuous spin representations of the Poincar\'e
algebra for massless particles in higher dimensions. The states are labeled
both by the length of a space-like translation vector and the Dynkin indices of
the {\it short little group} , where is the space-time dimension.
Continuous spin representations are in one-to-one correspondence with
representations of the short little group. We also demonstrate how combinations
of the bosonic and fermionic representations form supermultiplets of the
super-Poincar\'e algebra. If the light-cone translations are nilpotent, these
representations become finite dimensional, but contain zero or negative norm
states, and their supersymmetry algebra contains a central charge in four
dimensions.Comment: 19 page
Micro-scale flow cytometry-based and biochemical analysis of lipid signaling in primary B cell subpopulations
B cell subpopulations in the spleen have been extensively characterized phenotypically; however, biochemical properties of these cell populations following B cell antigen receptor engagement have not been fully determined due to technical difficulties and limiting cell numbers. We therefore employed mini-scale protocols to assess lipid signaling, particularly that of diacylglycerol and inositol trisphosphate, with as few as 0.5x106 purified early (T1) and late (T2) transitional B cells. Additionally, utilizing flow cytometric techniques, we determined levels of phosphatidylinositol bisphosphate and calcium mobilization in T1 and T2 cells, as well as mature follicular and marginal zone B cells using less than 1x106 primary B cells. Thus, these biochemical and flow cytometric methodologies can be used to analyse signal-induced changes in phosphatidylinositol bisphosphate levels, diacylglycerol and inositol triphosphate production and calcium in each B cell population
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A flexible organic reflectance oximeter array.
Transmission-mode pulse oximetry, the optical method for determining oxygen saturation in blood, is limited to only tissues that can be transilluminated, such as the earlobes and the fingers. The existing sensor configuration provides only single-point measurements, lacking 2D oxygenation mapping capability. Here, we demonstrate a flexible and printed sensor array composed of organic light-emitting diodes and organic photodiodes, which senses reflected light from tissue to determine the oxygen saturation. We use the reflectance oximeter array beyond the conventional sensing locations. The sensor is implemented to measure oxygen saturation on the forehead with 1.1% mean error and to create 2D oxygenation maps of adult forearms under pressure-cuff-induced ischemia. In addition, we present mathematical models to determine oxygenation in the presence and absence of a pulsatile arterial blood signal. The mechanical flexibility, 2D oxygenation mapping capability, and the ability to place the sensor in various locations make the reflectance oximeter array promising for medical sensing applications such as monitoring of real-time chronic medical conditions as well as postsurgery recovery management of tissues, organs, and wounds
Pushing the limit of instrument capabilities
Chemically Peculiar (CP) stars have been subject of systematic research since
more than 50 years. With the discovery of pulsation of some of the cool CP
stars, the availability of advanced spectropolarimetric instrumentation and
high signal- to-noise, high resolution spectroscopy, a new era of CP star
research emerged about 20 years ago. Together with the success in ground-based
observations, new space projects are developed that will greatly benefit for
future investigations of these unique objects. In this contribution we will
give an overview of some interesting results obtained recently from
ground-based observations and discuss on future outstanding Gaia space mission
and its impact on CP star research.Comment: Joint Discussion 04, Secsion 1, To appear in Highlights of Astronomy,
Proc. of the XXVIIth IAU General Assembly, Rio de Janeiro, Brazil, August
2009, 9 page
Tamm-Horsfall Protein Regulates Mononuclear Phagocytes in the Kidney
Tamm-Horsfall protein (THP), also known as uromodulin, is a kidney-specific protein produced by cells of the thick ascending limb of the loop of Henle. Although predominantly secreted apically into the urine, where it becomes highly polymerized, THP is also released basolaterally, toward the interstitium and circulation, to inhibit tubular inflammatory signaling. Whether, through this latter route, THP can also regulate the function of renal interstitial mononuclear phagocytes (MPCs) remains unclear, however. Here, we show that THP is primarily in a monomeric form in human serum. Compared with wild-type mice, THP-/- mice had markedly fewer MPCs in the kidney. A nonpolymerizing, truncated form of THP stimulated the proliferation of human macrophage cells in culture and partially restored the number of kidney MPCs when administered to THP-/- mice. Furthermore, resident renal MPCs had impaired phagocytic activity in the absence of THP. After ischemia-reperfusion injury, THP-/- mice, compared with wild-type mice, exhibited aggravated injury and an impaired transition of renal macrophages toward an M2 healing phenotype. However, treatment of THP-/- mice with truncated THP after ischemia-reperfusion injury mitigated the worsening of AKI. Taken together, our data suggest that interstitial THP positively regulates mononuclear phagocyte number, plasticity, and phagocytic activity. In addition to the effect of THP on the epithelium and granulopoiesis, this new immunomodulatory role could explain the protection conferred by THP during AKI
Thermal Monitoring of Embankment Dams by Fiber Optics
International audienceInternal erosion is the main cause of failure of earthen hydraulic structures. Moreover, it is often difficult for the operator to detect internal erosion at an early stage. For the last twenty years, leakage detection by thermometry has been developed mainly in Europe. The principle is based on the fact that a leakage through an embankment dam changes its temperature field. In this regard, fiber optics buried in the structures can be used as temperature sensors. Their principal advantage is distributed temperature measurements, at every meter along their length, and over long distances. Indeed, once deployed, optical fiber proves to be an effective mean of probing several kilometers, making it extremely useful for monitoring dikes. Various methods have been developed for analysis of temperature data acquired by these powerful sensors. Thesephysico-statistical and signal processing methods allow to propose a system for "early warning" or for long-term monitoring. Based on the results of several tests at controlled and industrial sites, this presentation will demonstrate the improvement of this surveillance methodology for the safety procedures of embankment dam
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