The role of thymus dependent and bone marrow derived lymphocytes in acquired tolerance

Imperial Users onl

A NEW ALGORITHM FOR COMPUTING COMPENSATED INCOME FROM ORDINARY DEMAND FUNCTIONS

This paper proposes a REversible Second-ORder Taylor (RESORT) expansion of the expenditure function to compute compensated income from ordinary demand functions as an alternative to the algorithm proposed by Vartia. These algorithms provide measures of Hicksian welfare changes and Konus-type cost of living indices. RESORT also validates the results by checking the matrix of compensated price effects. obtained through the Slutsky equation, for symmetry and negative semi-definiteness as required by expenditure minimization. In contrast, Vartia's algorithm provides no validation procedure. RESORT is similar to Vartia's algorithm in using price steps. It computes compensated income at each step "forward" from the initial to the terminal prices, and insures that the compensated income computed "backward" is equal to its value computed in the "forward" procedure. Thus, RESORT is "reversible" and guarantees unique values of compensated income for each set of prices and, as a result, also unique measures of welfare changes and cost of living indices. These unique results are not, however, guaranteed by the usual Taylor series expansion for computing compensated income.Research Methods/ Statistical Methods,

Relic density and CMB constraints on dark matter annihilation with Sommerfeld enhancement

We calculate how the relic density of dark matter particles is altered when their annihilation is enhanced by the Sommerfeld mechanism due to a Yukawa interaction between the annihilating particles. Maintaining a dark matter abundance consistent with current observational bounds requires the normalization of the s-wave annihilation cross section to be decreased compared to a model without enhancement. The level of suppression depends on the specific parameters of the particle model, with the kinetic decoupling temperature having the most effect. We find that the cross section can be reduced by as much as an order of magnitude for extreme cases. We also compute the mu-type distortion of the CMB energy spectrum caused by energy injection from such Sommerfeld-enhanced annihilation. Our results indicate that in the vicinity of resonances, associated with bound states, distortions can be large enough to be excluded by the upper limit |mu|<9.0x10^(-5) found by the COBE/FIRAS experiment.Comment: 10 pages, 6 figures, accepted for publication in Physical Review D. Corrections to eqs. 9,10,14 and 16. Figures updated accordingly. No major changes to previous results. Website with online tools for Sommerfeld-related calculations can be found at http://www.mpa-garching.mpg.de/~vogelsma/sommerfeld

Preparation of zinc-oxide and zinc-sulfide powders by controlled precipitation from aqueous-solution

Resumo não disponível..

Assessment and risk stratification of ageing-related target organ damage and adverse health outcomes in the general population

The objectives of this doctoral thesis are to address the contribution of blood pressure to the presence of subclinical target-organ damage and the development of adverse health complications that associate with a poor life course of aging. This thesis focuses on ambulatory blood pressure monitoring to provide the most accurate information about the blood pressure level and variability over a 24-hour period. Moreover, by investigating the role of novel markers, including imaging markers and biomarkers, this thesis also provides possible pathophysiological and biological mechanisms that might explain the association between vascular risk factors and adverse health complications. We envisage that the results of our study will contribute to the refinement of risk stratification of major micro- (ophthalmological, neurological) and macro‑vascular (neurological, cardiovascular) complications associated with poor aging

Simplification of EEG Signal Extraction, Processing, and Classification Using a Consumer-Grade Headset to Facilitate Student Engagement in BCI Research

Brain-computer interfaces (BCIs) are an emerging technology that leverage neurophysiological signals as input to computing systems. By circumventing the reliance on traditional input methods (e.g., mouse and keyboard), BCIs show a promising alternative interaction modality for people with disabilities. Advances in BCI research have further inspired a range of novel applications, such as the use of neurophysiological signals as passive input (e.g., to detect and reduce operator workload when managing multiple machines). BCIs have also emerged as a tool for student engagement due to the intrinsic interdisciplinarity of the technology, which spans the fields of computer science, electrical engineering, neuroscience, psychology and their broad applicability. However, these benefits also stand as a challenge to students interested in BCI research, as the need for familiarity with multiple related disciplines creates a high barrier to entry. Towards overcoming this barrier, we developed a simplified EEG-based BCI wherein we integrated a low-cost, consumer-grade headset for signal extraction with a novel graphical user interface that affords seamless exploration of several signal processing and machine learning techniques for analysis. Here, electrical activity is measured in real-time via an extracortical electrode placed on the user’s forehead, superior to the prefrontal cortex. The headset can then be connected to any Bluetooth-compatible device via a Bluetooth connection for (1) processing and classification of the signal contents and (2) operation of a machine (e.g., the Cozmo robot) via the intentional brain activity of the user. An additional visualization model also allows the user to explore the signal processing techniques, including the information decomposition and classification