279 research outputs found
On a reconstruction problem
No full textAbstractThis note supplements an earlier paper of this author, in which the concept of a strong k-hypomorphism between two graphs was defined (Thatte, 1990, Sectin VI). For k=1, this is just a hypomorphism. Here it is proved that strongly k-hypomorphic graphs and strongly k-edge hypomorphic directed graphs are isomorphic if k>1
A reconstruction problem related to balance equations II: The general case
No full textAbstractA modified k-deck of a graph G, first introduced in (Krasikov and Roditty, 1987), is obtained by removing k edges of G in all possible ways, and adding k (not necessarily new) edges in all possible ways. Krasikov and Roditty asked if it was possible to construct the usual k-edge deck of a graph from its modified k-deck. In (Thatte, to appear), the author solved this problem for the case when k = 1. In this paper, the problem is completely solved for arbitrary k. The proof makes use of the k-edge version of Lovász's result and the eigenvalues of certain matrix related to the Johnson graph
Chondrogenic Differentiation of Adult Mesenchymal Stem Cells and Embryonic Stem Cells
No full textMesenchymal stem cell (MSC) contraction associated with chondrogenesis is attributed to the expression of alpha-smooth muscle actin (alpha-SMA). In this study, pluripotent embryonic carcinoma cells (ECCs) and MSCs were compared for cartilage histogensis. Both cell types expressed alpha-SMA in monolayer. However, when cultured in pellets and in 3-D scaffolds, only MSCs contracted and formed glycosaminoglycan (GAG)- and type II collagen-rich tissue. Under these culture conditions, MSCs appear to be superior over ECCs for cartilage regeneration.United States. Dept. of Veteran Affair
Provenance-based trust for grid computing: Position Paper
No full textCurrent evolutions of Internet technology such as Web Services, ebXML, peer-to-peer and Grid computing all point to the development of large-scale open networks of diverse computing systems interacting with one another to perform tasks. Grid systems (and Web Services) are exemplary in this respect and are perhaps some of the first large-scale open computing systems to see widespread use - making them an important testing ground for problems in trust management which are likely to arise. From this perspective, today's grid architectures suffer from limitations, such as lack of a mechanism to trace results and lack of infrastructure to build up trust networks. These are important concerns in open grids, in which "community resources" are owned and managed by multiple stakeholders, and are dynamically organised in virtual organisations. Provenance enables users to trace how a particular result has been arrived at by identifying the individual services and the aggregation of services that produced such a particular output. Against this background, we present a research agenda to design, conceive and implement an industrial-strength open provenance architecture for grid systems. We motivate its use with three complex grid applications, namely aerospace engineering, organ transplant management and bioinformatics. Industrial-strength provenance support includes a scalable and secure architecture, an open proposal for standardising the protocols and data structures, a set of tools for configuring and using the provenance architecture, an open source reference implementation, and a deployment and validation in industrial context. The provision of such facilities will enrich grid capabilities by including new functionalities required for solving complex problems such as provenance data to provide complete audit trails of process execution and third-party analysis and auditing. As a result, we anticipate that a larger uptake of grid technology is likely to occur, since unprecedented possibilities will be offered to users and will give them a competitive edge
Fault Diagnosis of Semiconductor Random Access Memories
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Reason: Restricted to UIUC communityOpen Restriction set for Item 100821 on 2019-11-15T17:33:23Z with date null by [email protected] Services Electronics Program / DAAB-07-72-C-0259OpenCoordinated Science Laboratory was formerly known as Control Systems Laboratory"Author name appears as ""Satish Munkund Thatte"" in front matter
Characterization of the interaction of a TCR α chain variable domain with MHC II I-A molecules
No full textThe αβ TCR recognizes peptides bound to MHC molecules. In the present study, we analyzed the interaction of a soluble TCR α chain variable domain (V(α)4.2-J(α)40; abbreviated to V(α)4.2) with the MHC class II molecule I-A(u). V(α)4.2 bound specifically to I-A(u) expressed on the surface of a transfected thymoma cell line. Modifications in the amino acid residues located within the three complementarity-determining regions (CDRs) of the V(α) domain did not markedly affect this interaction. However, mutation of glutamic acid to alanine at position 69 of the fourth hypervariable region (HV4α) significantly increased the binding. Antibody inhibition studies suggested that the binding site was partly contributed by a region of the β chain of I-A(u). Furthermore, the binding of V(α)4.2 to the MHC molecule was dependent on the nature of the peptide bound in the groove. Soluble V(α)4.2 specifically inhibited the activation of TCR transfectants by I-A(u)-expressing cells pulsed with an N-terminal peptide of myelin basic protein. V(α)4.2 also bound to MHC class II-expressing spleen cell populations from mice of the H-2(u) and H-2(d) haplotypes. The binding of V(α)4.2 to I-A molecules might explain the immunoregulatory effects reported previously for TCR α chains. This V(α)4.2 interaction may also be relevant to models of antigen presentation involving the binding of intact proteins to MHC class II molecules followed by their processing to generate epitopes suitable for T cell recognition.</p
How To Touch a Running System
No full textThe increasing importance of distributed and decentralized software architectures entails more and more attention for adaptive software. Obtaining adaptiveness, however, is a difficult task as the software design needs to foresee and cope with a variety of situations. Using reconfiguration of components facilitates this task, as the adaptivity is conducted on an architecture level instead of directly in the code. This results in a separation of concerns; the appropriate reconfiguration can be devised on a coarse level, while the implementation of the components can remain largely unaware of reconfiguration scenarios.
We study reconfiguration in component frameworks based on formal theory. We first discuss programming with components, exemplified with the development of the cmc model checker. This highly efficient model checker is made of C++ components and serves as an example for component-based software development practice in general, and also provides insights into the principles of adaptivity. However, the component model focuses on high performance and is not geared towards using the structuring principle of components for controlled reconfiguration. We thus complement this highly optimized model by a message passing-based component model which takes reconfigurability to be its central principle.
Supporting reconfiguration in a framework is about alleviating the programmer from caring about the peculiarities as much as possible. We utilize the formal description of the component model to provide an algorithm for reconfiguration that retains as much flexibility as possible, while avoiding most problems that arise due to concurrency. This algorithm is embedded in a general four-stage adaptivity model inspired by physical control loops. The reconfiguration is devised to work with stateful components, retaining their data and unprocessed messages. Reconfiguration plans, which are provided with a formal semantics, form the input of the reconfiguration algorithm. We show that the algorithm achieves perceived atomicity of the reconfiguration process for an important class of plans, i.e., the whole process of reconfiguration is perceived as one atomic step, while minimizing the use of blocking of components. We illustrate the applicability of our approach to reconfiguration by providing several examples like fault-tolerance and automated resource control
New Photometry and Spectra of AB Doradus C: An Accurate Mass Determination of a Young Low-Mass Object with Theoretical Evolutionary Tracks
No full textWe present new photometric and spectroscopic measurements for the unique, young, low-mass evolutionary track calibrator AB Dor C. While the new Ks photometry is similar to that previously published in Close et al. (2005) the spectral type is found to be earlier. Based on new H and K IFS spectra of AB Dor C (Thatte et al. 2007; paper 1) we adopt a spectral type of M5.5+/-1.0 for AB Dor C. This is considerably earlier than the M8+/-1 estimated in Close et al. (2005) and Nielsen et al. (2005) yet is consistent with the M6+/-1 independently derived by Luhman and Potter (2005). However, the spectrum presented in paper 1 and analyzed here is a significant improvement over any previous spectrum of AB Dor C. We also present new astrometry for the system which further supports a 0.090+/-0.005 Msun mass for the system. Once armed with an accurate spectrum and Ks flux we find L=0.0021+/-0.0005 Lsun and Teff=2925{+170}{-145}K for AB Dor C. These values are consistent with a ~75 Myr 0.090+/-0.005 Msun object like AB Dor C according to the DUSTY evolutionary tracks (Chabrier et al. 2000). Hence masses can be estimated from the HR diagram with the DUSTY tracks for young low-mass objects like AB Dor C. However, we cautiously note that underestimates of the mass from the tracks can occur if one lacks a proper (continuum preserved) spectra or is relying on NIR fluxes alone
Unfavourable results in pollicisation
No full textPollicisation of the index finger is perhaps one of the most complex and most rewarding operations in hand and plastic surgery. It however has a steep learning curve and demands very high skill levels and experience. There are multiple pitfalls and each can result in an unfavourable result. In essence we need to: Shorten the Index, recreate the carpo metacarpal joint from the metacarpo phalangeal (MP) joint, rotate the digit by about 120° for pulp to pulp pinch, palmarly abduct by 40-50° to get a new first web gap, Shorten and readjust the tension of the extensors, re attach the intrinsics to form a thenar eminence capable of positioning the new thumb in various functional positions and finally close the flaps forming a new skin envelope. The author has performed over 75 pollicisations personally and has personal experience of some of the issues raised there. The steps mentioned therefore are an algorithm for helping the uninitiated into these choppy waters
Science with integral field spectrographs present and future
No full textIn the first part of this thesis we use the Oxford Short Wavelength Integral Field spec-
Trograph (SWIFT) to trace radial variations of initial mass function (IMF) sensitive stellar
absorption features in several galaxies. We observe M31 and M32, the two massive Coma
brightest cluster galaxies (BCGs), NGC4889 and NGC4874, and the BCG in the Coma
south-west cluster NGC4839. We measure equivalent widths of the sodium NaI λ8190 doublet,
calcium triplet CaT λ8498, 8542, 8662 and Wing-Ford band FeH λ9916. In M31 we
find a strong NaI gradient within the central 10 arcsec (38 pc) in contrast to a
at FeH profile. M32 displays
at profiles for all three indices, with similar FeH but lower NaI strengths
compared with M31. Using stellar population synthesis (SPS) models we find that M31
and M32 are well described by a Chabrier IMF throughout, although M31 displays a strong
negative gradient in Na abundance within the inner 30 pc reaching [Na/Fe] ∼ +1:0 at the
centre. Within NGC4889 we again find a strong NaI gradient and flat FeH profile and derive
a Chabrier, or even bottom-light IMF, with a strong Na abundance gradient. This suggests
conflict with recent evidence for an increased IMF slope with increased velocity dispersion
in early type galaxies. We also infer a Chabrier IMF for NGC4874. However, for NGC4839
we measure both strong NaI and strong FeH, which may be evidence for a bottom-heavy
IMF. The IMFs we infer for the BCGs are supported by optical index measurements and
dynamical modelling results from the literature. Our galaxies cover a wide range of central
velocity dispersions (60-400kms-1) and we find no IMF variation at both lowest and
highest masses, with only one galaxy showing evidence for a bottom-heavy IMF.
In the second part we present HSIM: a dedicated pipeline for simulating observations
with HARMONI on the European ELT. HSIM takes high spectral and spatial resolution
input data cubes, encoding physical descriptions of astrophysical sources, and incorporates
detailed models of the sky, telescope and instrument to produce realistic mock data cubes.
We employ a new method of incorporating the strongly wavelength dependent adaptive
optics point spread functions. HSIM provides an advancement upon traditional exposure
time calculators and allows us to predict the feasibility of a given observing programme
with HARMONI through the full analysis of mock data. We use HSIM to predict the
performance of the current HARMONI design, through point source sensitivities and noise
regimes for each operating mode. We find that HARMONI will be predominately read-out
noise limited in the R- and H-bands, but heavily background-limited for the majority of K-
band modes. The coarsest 30x60 mas spatial scale offers background-limited observations
in all bands. We compare the visible wavelength AO performance between HARMONI and
MUSE, finding that HARMONI offers improved sensitivity at Hα, and longer, wavelengths.
Lastly, we perform a suite of HSIM simulations of star-forming emission-line galaxies at
z ∼2-3. We detail the construction of input data cubes using two separate generation
methods. We show that HARMONI will provide exquisite resolved spectroscopy of these
objects, probing and deriving properties of individual star forming complexes down to at
least ∼ 350 pc in size. It will be possible to spatially resolve the sub-kpc star-forming
complexes of multiple bright galaxies in a single night, which represents a large increase in
observing efficiency over current telescopes and instruments.</p
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