bluuebunny/crossref_metadata_2025 huggingface dataset:
Oritavancin Population Pharmacokinetics in Healthy Subjects and Patients with Complicated Skin and Skin Structure Infections or Bacteremia
Authors: Rubino Christopher M. , Van Wart Scott A. , Bhavnani Sujata M. , Ambrose Paul G. , McCollam Jill S. , Forrest Alan
Published: July 2009

Oritavancin is a novel glycopeptide antimicrobial agent with potent in vitro activity against a wide variety of gram-positive bacteria, including multidrug-resistant strains of staphylococci and enterococci. A population pharmacokinetic model was developed to describe the disposition of oritavancin with data from a pooled population of phase 1 healthy subjects and phase 2 and 3 patients with complicated skin and skin structure infections or
Staphylococcus aureus
bacteremia. In addition, the potential influence of factors such as the subject's age, gender, and clinical laboratory measures on oritavancin disposition was evaluated. Oritavancin was administered as both single- and multiple-dose intravenous (i.v.) infusions in fixed doses ranging from 100 to 800 mg or weight-based doses ranging from 0.02 to 10 mg/kg of body weight, with infusion durations ranging from 0.13 to 6.5 h across all studies. The most robust fit to the data (
n
= 6,290 oritavancin plasma concentrations from 560 subjects) was obtained using a three-compartment model with zero-order i.v. infusion and first-order elimination. The model was parameterized using total clearance (CL), volume of central compartment (Vc), distributional clearances from the central to both the first and second peripheral compartments, and volumes of distribution for both the first and second peripheral compartments. Weight and study phase (phase 1 versus phase 2/3) were identified as significant predictors of the interindividual variability in CL, while body surface area and age were significant for Vc. These results suggest that dose modification may be warranted in patients weighing >110 kg. However, the mild nature of the observed relationships for Vc suggest that dosing adjustments are not necessary for elderly patients.
In Vitro 24-Hour Time-Kill Studies of Vancomycin and Linezolid in Combination versus Methicillin-Resistant
Staphylococcus aureus
Authors: Singh Shveta Rani , Bacon Alfred E. , Young David C. , Couch Kimberly A.
Published: July 2009

Many clinicians are trying unique strategies, including vancomycin and linezolid in combination, for treatment of patients who do not respond to conventional therapy against methicillin (meticillin)-resistant
Staphylococcus aureus
. In our study, which illustrated in vitro activity only, no synergistic activity was seen when the two agents were combined. Conversely, antagonistic activity occurred in three of five strains when linezolid was added to vancomycin. Our results indicate that vancomycin and linezolid in combination should be avoided.
Evaluation of Vancomycin and Daptomycin Potency Trends (MIC Creep) against Methicillin-Resistant
Staphylococcus aureus
Isolates Collected in Nine U.S. Medical Centers from 2002 to 2006
Authors: Sader Helio S. , Fey Paul D. , Fish Douglas N. , Limaye Ajit P. , Pankey George , Rahal James , Rybak Michael J. , Snydman David R. , Steed Lisa L. , Waites Ken , Jones Ronald N.
Published: July 2009

Vancomycin MIC creep has been reported by some institutions but not confirmed in large surveillance studies. We evaluated the possible occurrence of MIC creep when testing vancomycin and daptomycin against methicillin (oxacillin)-resistant
Staphylococcus aureus
(MRSA) by using precise incremental reference MIC methods. Nine hospitals (one in each U.S. census region) randomly selected bloodstream MRSA strains (target, 40/year) from 2002 to 2006. MICs were determined by the reference broth microdilution method using incremental dilutions (eight for each log
2
dilution step). Isolates for which vancomycin MICs were >1 μg/ml were typed by pulsed-field gel electrophoresis (PFGE). The vancomycin MIC mode was either 0.625 μg/ml (for eight hospitals) or 0.813 μg/ml (for one hospital), and vancomycin MIC results for 72.9% of strains were between 0.563 and 0.688 μg/ml. No yearly variation in the central tendency of vancomycin MICs for the wild-type population in any medical center was observed; however, when data were analyzed by the geometric mean statistic, vancomycin MIC increases (at three sites) and declines (at three sites) were observed. The daptomycin MIC mode varied from 0.156 μg/ml (2003 to 2005) to 0.219 μg/ml (2002 and 2006), and MIC results for 83.5% (80.3 to 89.2% in each of the centers) of isolates fell between these values. Among PFGE-typed strains, 43 of 55 (78%; from seven hospitals) showed a pattern consistent with that of the USA100 clone, which was represented by all strains from two hospitals and 64 to 88% of strains from five other medical centers; only one strain (2%) was USA300. In conclusion, the perception of MIC creep may vary according to the methods used to analyze the data. Geometric mean MIC data revealed a possible, very-low-level MIC creep at three of nine sites over the 5-year period, which was not evident using modal MICs or the data from all nine hospitals (+0.02 μg/ml). The occurrence of isolates for which the vancomycin MIC was >1 μg/ml was very unusual, with no increased trend, but these organisms were usually clonal (USA100).
In Vitro Antiviral Activity of V-073 against Polioviruses
Authors: Oberste M. Steven , Moore Deborah , Anderson Barbara , Pallansch Mark A. , Pevear Daniel C. , Collett Marc S.
Published: July 2009

V-073, an enterovirus capsid inhibitor, was evaluated for its spectrum of antipoliovirus activity. V-073 inhibited all 45 polioviruses tested in a virus-induced cytopathic effect protection assay, with 50% effective concentration (EC
50
) values ranging from 0.003 to 0.126 μM. Ninety percent of the polioviruses tested were inhibited at EC
50
s of ≤0.076 μM (MIC
90
= 32 ng/ml). V-073 is a promising antiviral candidate for the posteradication management of poliovirus incidents.
Impact of Low-Level Resistance to Fluoroquinolones Due to
qnrA1
and
qnrS1
Genes or a
gyrA
Mutation on Ciprofloxacin Bactericidal Activity in a Murine Model of
Escherichia coli
Urinary Tract Infection
Authors: Allou Nicolas , Cambau Emmanuelle , Massias Laurent , Chau Françoise , Fantin Bruno
Published: July 2009

We investigated the impact of low-level resistance to fluoroquinolones on the bactericidal activity of ciprofloxacin in a murine model of urinary tract infection. The susceptible
Escherichia coli
strain CFT073 (ciprofloxacin MIC [CIP MIC] of 0.008 μg/ml) was compared to its transconjugants harboring
qnrA1
or
qnrS1
and to an S83L
gyrA
mutant. The three derivatives showed similar low-level resistance to fluoroquinolones (CIP MICs, 0.25 to 0.5 μg/ml). Bactericidal activity measured in vitro after 1, 3, and 6 h of exposure to 0.5 μg/ml of ciprofloxacin was significantly lower for the derivative strains (
P
< 0.01). In the murine model of urinary tract infection (at least 45 mice inoculated per strain), mice were treated with a ciprofloxacin regimen of 2.5 mg/kg, given subcutaneously twice daily for 2 days. In mice infected with the susceptible strain, ciprofloxacin significantly decreased viable bacterial counts (log
10
CFU/g of tissue) in the bladder (4.2 ± 0.5 versus 5.5 ± 1.3;
P
= 0.001) and in the kidney (3.6 ± 0.8 versus 5.0 ± 1.1;
P
= 0.003) compared with those of untreated mice. In contrast, no significant decrease in viable bacterial counts was observed with any of the three derivative strains. The area under the concentration-time curve from 0 to 24 h/MIC and the maximum concentration of drug in serum/MIC ratios measured in plasma were indeed equal to 827 and 147, respectively, for the parental strain, and only 12.4 to 24.8 and 2.2 to 4.4, respectively, for the derivative strains. In conclusion, low-level resistance to fluoroquinolones conferred by a
qnr
gene is associated with decreased bactericidal activity of ciprofloxacin, similar to that obtained with a
gyrA
mutation.
Actin Dynamics and Rho GTPases Regulate the Size and Formation of Parasitophorous Vacuoles Containing
Coxiella burnetii
Authors: Aguilera Milton , Salinas Romina , Rosales Eliana , Carminati Sergio , Colombo Maria I. , Berón Walter
Published: July 2009

Q fever is a disease caused by
Coxiella burnetii
. In the host cell, this pathogen generates a large parasitophorous vacuole (PV) with lysosomal characteristics. Here we show that F-actin not only is recruited to but also is involved in the formation of the typical PV. Treatment of infected cells with F-actin-depolymerizing agents alters PV development. The small PVs formed in latrunculin B-treated cells were loaded with transferrin and Lysotracker and labeled with an antibody against cathepsin D, suggesting that latrunculin B did not affect vacuole cargo and its lysosomal characteristics. Nevertheless, the vacuoles were unable to fuse with latex bead phagosomes. It is known that actin dynamics are regulated by the Rho family GTPases. To assess the role of these GTPases in PV formation, infected cells were transfected with pEGFP expressing wild-type and mutant Rac1, Cdc42, and RhoA proteins. Rac1 did not show significant PV association. In contrast, PVs were decorated by both the wild types and constitutively active mutants of Cdc42 and RhoA. This association was inhibited by treatment of infected cells with chloramphenicol, suggesting a role for bacterial protein synthesis in the recruitment of these proteins. Interestingly, a decrease in vacuole size was observed in cells expressing dominant-negative RhoA; however, these small vacuoles accumulated transferrin, Lysotracker, and DQ-BSA. In summary, these results suggest that actin, likely modulated by the GTPases RhoA and Cdc42 and by bacterial proteins, is involved in the formation of the typical PV.
Improved method for assessing iron stores in the bone marrow
Authors: Phiri K S , Calis J C J , Kachala D , Borgstein E , Waluza J , Bates I , Brabin B , van Hensbroek M Boele
Published: July 2009

Background:

Bone marrow iron microscopy has been the “gold standard” method of assessing iron deficiency. However, the commonly used method of grading marrow iron remains highly subjective.

Aim:

To improve the bone marrow grading method by developing a detailed protocol that assesses iron in fragments, in macrophages around fragments and in erythroblasts.

Methods:

A descriptive study of marrow aspirates of 303 children (aged 6–60 months) with severe anaemia and 22 controls (children undergoing elective surgery) was conducted at hospitals in southern Malawi (2002–04).

Results:

Using an intensive marrow iron grading method, 22% and 39% of cases and controls had deficient iron stores, and 40% and 46% had functional iron deficiency, respectively. Further evaluation of the iron status classification by the intensive method showed that functional iron deficiency was associated with significantly increased C-reactive protein concentrations (126.7 (85.6) mg/l), and iron stores deficiency with significantly increased soluble transferrin receptor concentrations (21.7 (12.5) μg/ml).

Conclusions:

Iron assessment can be greatly improved by a more intense marrow examination. This provides a useful iron status classification which is of particular importance in areas where there is a high rate of inflammatory conditions.
Appropriateness of antineutrophil cytoplasmic antibody testing in a tertiary hospital
Authors: Robinson P C , Steele R H
Published: July 2009

Aims:

To determine whether indications for ordering antineutrophil cytoplasmic antibodies (ANCA) meet the 1999 guidelines proposed for ANCA testing; and to examine the test characteristics of the ANCA test.

Methods:

The indications for all ANCA tests over a two-year period were assessed and compared to the 1999 guidelines for the appropriate testing of ANCA.

Results:

1127 tests were examined. Overall 33.4% had an indication meeting the 1999 guidelines. The commonest non-guideline indications were ocular or orbital inflammation, liver disease and inflammatory bowel disease. All tests with a positive ANCA had indications for testing in line with the 1999 guidelines. In all but one case an ANCA associated small vessel vasculitis (AASVV) was present.

Conclusions:

ANCA is ordered for a wide range of guideline and non-guideline indications. No cases of AASVV would have been missed if ordering were restricted to tests meeting the 1999 guidelines.
MGMT methylation in diffuse large B-cell lymphoma: validation of quantitative methylation-specific PCR and comparison with MGMT protein expression
Authors: Uccella S , Cerutti R , Placidi C , Marchet S , Carnevali I , Bernasconi B , Proserpio I , Pinotti G , Tibiletti M G , Furlan D , Capella C
Published: July 2009

Aims:

(1) To validate a quantitative real time methylation specific PCR assay (MethyLight) for the detection of O6-methylguanine-DNA methyltransferase (MGMT) gene methylation status (MS) in diffuse large B-cell lymphoma (DLBCL). (2) To determine the immunohistochemical (IHC) expression of the MGMT protein and correlate it with MS. Both IHC and MethyLight results were compared with patient’s outcome.

Methods:

71 patients with primary nodal DLBCL were studied. MGMT immunoreactivity was detected using a specific monoclonal antibody. The MS of MGMT gene was analysed in 52/71 DLBCL using MethyLight. A selected subset of 40 DLBCL was also analysed using qualitative methylation-specific PCR (MSP). Statistical analysis of overall survival (OS), lymphoma-specific survival (LSS) and progression free survival (PFS) was performed according to IHC and MS results.

Results:

19/71 DLBCLs (27%) were MGMT-negative at IHC; all were analysed, together with 33/52 MGMT-positive DLBCLs. MethyLight showed a better performance than MSP. There was a good correlation between the presence of MGMT expression and the unmethylated status; the absence of IHC expression was poorly correlated with the presence of methylation. Better OS, LSS and PFS was found in DLBCLs with MGMT gene methylation. DLBCLs not expressing MGMT at IHC showed a longer PFS.

Conclusions:

The quantitative real-time methylation-specific PCR assay for the detection of MGMT gene hypermethylation has been validated for the first time in DLBCL. Immunohistochemistry seems to represent an useful preliminary test to identify unmethylated cases; MS analysis may be performed in non-immunoreactive cases to identify truly methylated DLBCLs, which bear a better prognosis.
Aberrations of theMYCgene in unselected cases of diffuse large B-cell lymphoma are rare and unpredictable by morphological or immunohistochemical assessment
Authors: Obermann E C , Csato M , Dirnhofer S , Tzankov A
Published: July 2009

Diffuse large B-cell lymphomas (DLBCL) with aberrations ofMYCprobably represent a distinct clinicopathological entity following an aggressive course. Their incidence in unselected DLBCL collectives is debatable and the identification of such cases may be difficult. Therefore, the molecular epidemiology ofMYCaberrations in DLBCL and whether they can be predicted by morphology and immunohistochemistry were studied on tissue microarrays containing 333 cases. Evaluation ofMYCby fluorescence in situ hybridisation was successful in 220/333 (66%) cases. 9/220 (4%) cases showedMYCbreaks. Re-evaluation of these tumours did not show any specific morphological and/or immunohistochemical features. The median survival time was 9 months for the respective patients, as opposed to 80 for patients withoutMYCbreaks. The presence ofMYCbreaks in DLBCL cannot be reliably predicted by conventional methods. Since such patients might profit from different forms of treatment, routine testing of all DLBCL forMYCaberrations is suggested.
Immunophenotype of neoplastic plasma cells in AL amyloidosis
Authors: Deshmukh M , Elderfield K , Rahemtulla A , Naresh K N
Published: July 2009

Aim:

AL amyloidosis (ALA) is a form of plasma cell (PC) dyscrasia characterised by deposition of insoluble fibrillar deposits in various organs causing organ damage. This is believed to be the first study to evaluate the expression of CD79a, CD20, CD56, cyclin D1 and epithelial membrane antigen (EMA) in neoplastic PCs of ALA.

Methods and Results:

The study included 36 well-documented cases of ALA. In all cases presence of amyloid deposits had been documented by Congo Red stain in the bone marrow trephine biopsy (BMTB) and/or in other tissues. BMTBs showed varying degrees of PC infiltration (median 12%). In eight of the 36 cases with associated myeloma, the mean (2×SE) percentage of PCs (PC%) was 34 (18)%, while in the remaining, PC% was 15 (4)%. Expression of CD20, CD79a, CD56, cyclin D1 and EMA was noted in 42%, 86%, 50%, 53% and 83% of cases, respectively. Aberrant antigen expression in the form of CD56 and/or cyclin D1 expression was seen in 79% of cases. Nine of 10 cases with small lymphoid-like PCs were positive for CD20 and all the 10 cases were positive for cyclin D1. On the other hand, among cases without small lymphoid-like morphology, CD20 and cyclin D1 expression was seen in only 6 of 26 and 8 of 26 cases respectively (p = 0.001 and 0.002 respectively). CD20 expression correlated with cyclin D1 expression (p = 0.045). Cytological atypia/pleomorphism was predictive of associated myeloma (p = <0.001).

Conclusion:

Marrow involvement by neoplastic PCs in ALA can be identified by their aberrant antigen expression apart from light chain restriction, and rituximab as a possible treatment option may be explored in CD20-positive ALA.
Cyclo-oxygenase-2 overexpression is a feature of early and well-differentiated hepatocellular carcinoma with a favourable prognosis
Authors: Schmitz K J , Wohlschlaeger J , Lang H , Sotiropoulos G C , Kaiser G M , Schmid K W , Baba H A
Published: July 2009

Aims:

To determine the prognostic relevance of cyclo-oxygenase-2 (COX-2) expression in hepatocellular carcinoma (HCC) and its relationship to important clinicopathological parameters.

Methods:

A series of 196 patients with HCCs treated either by surgical resection (n = 106) or liver transplantation (n = 90) was investigated. Immunohistochemically confirmed COX-2 expression was correlated with a series of clinicopathologically relevant parameters as well as proliferative activity and apoptosis.

Results:

Overexpression of COX-2 correlated statistically with high histological tumour differentiation (p<0.001) and early TNM stage (p = 0.003). COX-2 overexpression was associated with lower apoptotic rates (p = 0.001), whereas proliferation activity did not differ significantly. In addition, COX-2 overexpression showed a significant correlation with favourable overall survival (p<0.001). In multivariate survival analysis, COX-2 expression qualified as an independent prognostic parameter (p = 0.030).

Conclusions:

Overexpression of COX-2 in HCC indicates early-stage cancer with less aggressive tumour behaviour and constitutes an independent prognostic factor.
DEHN SURGERIES ON 2-BRIDGE LINKS WHICH YIELD REDUCIBLE 3-MANIFOLDS
Authors: GODA HIROSHI , HAYASHI CHUICHIRO , SONG HYUN-JONG
Published: July 2009

We completely determine which Dehn surgeries on 2-bridge links yield reducible 3-manifolds. Further, we consider which surgery on one component of a 2-bridge link yields a torus knot, a cable knot and a satellite knot in this paper.
UNIVERSAL REPRESENTATIONS OF BRAID AND BRAID-PERMUTATION GROUPS
Authors: BERCEANU BARBU , PAPADIMA ŞTEFAN
Published: July 2009

Drinfel'd used associators to construct families of universal representations of braid groups. We consider semi-associators (i.e. we drop the pentagonal axiom and impose a normalization in degree one). We show that the process may be reversed, to obtain semi-associators from universal representations of 3-braids. We view braid groups as subgroups of braid-permutation groups. We construct a family of universal representations of braid-permutation groups, without using associators. All representations in the family are faithful, defined over ℚ by simple explicit formulae. We show that they give universal Vassiliev-type invariants for braid-permutation groups.
ANT COLONY OPTIMIZATION ALGORITHM FOR HETEROGENEOUS REDUNDANCY ALLOCATION IN MULTI-STATE SERIES-PARALLEL SYSTEMS
Authors: AGARWAL MANJU , SHARMA VIKAS K.
Published: July 2009

This paper addresses the redundancy allocation problem of multi-state series-parallel reliability structures where each subsystem can consist of maximum two types of redundant components. The objective is to minimize the total investment cost of system design satisfying system reliability constraint and the consumer load demand. The demand distribution is presented as a piecewise cumulative load curve. The configuration uses the binary components from a list of available products to provide redundancy so as to increase system reliability. The components are characterized by their feeding capacity, reliability and cost. A system that consists of elements with different reliability and productivity parameters has the capacity strongly dependent upon the selection of components constituting its structure. An ant colony optimization algorithm has been presented to analyze the problem and suggest an optimal system structure. The solution approach consists of a series of simple steps as used in early ant colony optimization algorithms dealing with other optimization problems and still proves efficient over the prevalent methods with regard to solutions obtained/computation time. Three multi-state system design problems have been solved for illustration.
Empirical Performance of the Constant Elasticity Variance Option Pricing Model
Authors: Chen Ren-Raw , Lee Cheng-Few , Lee Han-Hsing
Published: July 2009

In this essay, we empirically test the Constant–Elasticity-of-Variance (CEV) option pricing model by Cox (1975, 1996 ) and Cox and Ross (1976), and compare the performances of the CEV and alternative option pricing models, mainly the stochastic volatility model, in terms of European option pricing and cost-accuracy based analysis of their numerical procedures.

In European-style option pricing, we have tested the empirical pricing performance of the CEV model and compared the results with those by Bakshi et al. (1997). The CEV model, introducing only one more parameter compared with Black-Scholes formula, improves the performance notably in all of the tests of in-sample, out-of-sample and the stability of implied volatility. Furthermore, with a much simpler model, the CEV model can still perform better than the stochastic volatility model in short term and out-of-the-money categories. When applied to American option pricing, high-dimensional lattice models are prohibitively expensive. Our numerical experiments clearly show that the CEV model performs much better in terms of the speed of convergence to its closed form solution, while the implementation cost of the stochastic volatility model is too high and practically infeasible for empirical work.

In summary, with a much less implementation cost and faster computational speed, the CEV option pricing model could be a better candidate than more complex option pricing models, especially when one wants to apply the CEV process for pricing more complicated path-dependent options or credit risk models.
On the Relationship between Stock Prices and Exchange Rates for India
Authors: Narayan Paresh Kumar
Published: July 2009

In this paper, we apply several variants of the EGARCH model to examine the role of depreciation of the Indian rupee on India's stock market returns using daily data. Our findings suggest that volatility persistence has been high; depreciation of the rupee has increased volatility; and asymmetric volatility confirms that negative shocks generate more volatility than positive shocks. We also find that an appreciation of the Indian rupee over the 2002 to 2006 has generated more returns and less volatility.
DSC ANALYSIS FOR BUCKLING AND VIBRATION OF RECTANGULAR PLATES WITH ELASTICALLY RESTRAINED EDGES AND LINEARLY VARYING IN-PLANE LOADING
Authors: LAI S. K. , XIANG Y.
Published: July 2009

This paper presents the discrete singular convolution (DSC) method for solving buckling and vibration problems of rectangular plates with all edges transversely supported and restrained by uniform elastic rotational springs. The opposite plate edges are subjected to a linearly varying uni-axial in-plane loading. The rationale for using DSC method stems from its numerical stability and flexible implementation for structural analysis. To verify the present approach, convergence and comparison studies for rectangular plates with different combinations of elastically restrained and classical edges are carried out. Accurate buckling and vibration solutions of plates having two opposite edges elastically restrained and the other two sides clamped, or all edges elastically restrained are presented.
SECOND-ORDER ANALYSIS FOR DESIGN OF GLASS-SUPPORTING AND PRE-TENSIONED TRUSSES
Authors: LIU Y. P. , CHAN S. L.
Published: July 2009

Glass wall supporting systems, comprising of pre-tensioned high strength trusses made from alloy steel bars, behave nonlinearly under wind and other loads. For a proper analysis and design, second-order and large deflection analyses are mandatory as the structural response like stress and deflections are highly dependent on the small movements and temperature effects. Also, careful consideration must be given to various effects such as support settlement due to live loads and material creep, temperature change, pre-tension force and wind pressure. It is not uncommon to see many glass wall systems fail in a simulated wind load test under the simulated design wind speed. This paper presents a rigorous analysis and design of this type of structural systems used in two projects in Hong Kong. The key message is the need to use "section strength check" in place of the member design adopted in the conventional effective length method for design of practical structures behaving nonlinearly since the prescriptive buckling check formulae become inaccurate or even invalid. The use of stability function allowing for initial imperfections in place of cubic Hermite element is proposed here because of the high degree of nonlinearity.
Gaussian KD-trees for fast high-dimensional filtering
Authors: Adams Andrew , Gelfand Natasha , Dolson Jennifer , Levoy Marc
Published: July 2009

We propose a method for accelerating a broad class of non-linear filters that includes the bilateral, non-local means, and other related filters. These filters can all be expressed in a similar way: First, assign each value to be filtered a position in some vector space. Then, replace every value with a weighted linear combination of all values, with weights determined by a Gaussian function of distance between the positions. If the values are pixel colors and the positions are (
x, y
) coordinates, this describes a Gaussian blur. If the positions are instead (
x, y, r, g, b
) coordinates in a five-dimensional space-color volume, this describes a bilateral filter. If we instead set the positions to local patches of color around the associated pixel, this describes non-local means. We describe a Monte-Carlo kd-tree sampling algorithm that efficiently computes any filter that can be expressed in this way, along with a GPU implementation of this technique. We use this algorithm to implement an accelerated bilateral filter that respects full 3D color distance; accelerated non-local means on single images, volumes, and unaligned bursts of images for denoising; and a fast adaptation of non-local means to geometry. If we have
n
values to filter, and each is assigned a position in a
d
-dimensional space, then our space complexity is
O(dn
) and our time complexity is
O(dn
log
n
), whereas existing methods are typically either exponential in
d
or quadratic in
n
.
Kernel Nyström method for light transport
Authors: Wang Jiaping , Dong Yue , Tong Xin , Lin Zhouchen , Guo Baining
Published: July 2009

We propose a kernel Nyström method for reconstructing the light transport matrix from a relatively small number of acquired images. Our work is based on the generalized Nyström method for low rank matrices. We introduce the light transport kernel and incorporate it into the Nyström method to exploit the nonlinear coherence of the light transport matrix. We also develop an adaptive scheme for efficiently capturing the sparsely sampled images from the scene. Our experiments indicate that the kernel Nyström method can achieve good reconstruction of the light transport matrix with a few hundred images and produce high quality relighting results. The kernel Nyström method is effective for modeling scenes with complex lighting effects and occlusions which have been challenging for existing techniques.
Variational harmonic maps for space deformation
Authors: Ben-Chen Mirela , Weber Ofir , Gotsman Craig
Published: July 2009

A space deformation is a mapping from a source region to a target region within Euclidean space, which best satisfies some userspecified constraints. It can be used to deform shapes embedded in the ambient space and represented in various forms -- polygon meshes, point clouds or volumetric data. For a space deformation method to be useful, it should possess some natural properties: e.g. detail preservation, smoothness and intuitive control. A harmonic map from a domain ω ⊂
R

d

to
R

d

is a mapping whose
d
components are harmonic functions. Harmonic mappings are smooth and regular, and if their components are coupled in some special way, the mapping can be detail-preserving, making it a natural choice for space deformation applications. The challenge is to find a harmonic mapping of the domain, which will satisfy constraints specified by the user, yet also be detail-preserving, and intuitive to control. We generate harmonic mappings as a linear combination of a set of harmonic basis functions, which have a closed-form expression when the source region boundary is piecewise linear. This is done by defining an energy functional of the mapping, and minimizing it within the linear span of these basis functions. The resulting mapping is harmonic, and a natural "As-Rigid-As-Possible" deformation of the source region. Unlike other space deformation methods, our approach does not require an explicit discretization of the domain. It is shown to be much more efficient, yet generate comparable deformations to state-of-the-art methods. We describe an optimization algorithm to minimize the deformation energy, which is robust, provably convergent, and easy to implement.
Directable, high-resolution simulation of fire on the GPU
Authors: Horvath Christopher , Geiger Willi
Published: July 2009

The simulation of believable, photorealistic fire is difficult because fire is highly detailed, fast-moving, and turbulent. Traditional gridbased simulation models require large grids and long simulation times to capture even the coarsest levels of detail. In this paper, we propose a novel combination of coarse particle grid simulation with very fine, view-oriented refinement simulations performed on a GPU. We also propose a simple, GPU-based volume rendering scheme. The resulting images of fire produced by the proposed techniques are extremely detailed and can be integrated seamlessly into film-resolution images.

Our refinement technique takes advantage of perceptive limitations and likely viewing behavior to split the refinement stage into separable, parallel tasks. Multiple independent GPUs are employed to rapidly refine final simulations for rendering, allowing for rapid artist turnaround time and very high resolutions.

Directability is achieved by allowing virtually any user-defined particle behavior as an input to the initial coarse simulation. The physical criteria enforced by the coarse stage are minimal and could be easily implemented using any of the wide variety of commercially available fluid simulation tools. The GPU techniques utilized by our refinement stage are simple and widely available on even consumer-grade GPUs, lowering the overall implementation cost of the proposed system.
Optimizing content-preserving projections for wide-angle images
Authors: Carroll Robert , Agrawal Maneesh , Agarwala Aseem
Published: July 2009

Any projection of a 3D scene into a wide-angle image unavoidably results in distortion. Current projection methods either bend straight lines in the scene, or locally distort the shapes of scene objects. We present a method that minimizes this distortion by adapting the projection to content in the scene, such as salient scene regions and lines, in order to preserve their shape. Our optimization technique computes a spatially-varying projection that respects user-specified constraints while minimizing a set of energy terms that measure wide-angle image distortion. We demonstrate the effectiveness of our approach by showing results on a variety of wide-angle photographs, as well as comparisons to standard projections.
Symmetric tiling of closed surfaces
Authors: van Wijk Jarke J.
Published: July 2009

A regular map is a tiling of a closed surface into faces, bounded by edges that join pairs of vertices, such that these elements exhibit a maximal symmetry. For genus 0 and 1 (spheres and tori) it is well known how to generate and present regular maps, the Platonic solids are a familiar example. We present a method for the generation of space models of regular maps for genus 2 and higher. The method is based on a generalization of the method for tori. Shapes with the proper genus are derived from regular maps by tubification: edges are replaced by tubes. Tessellations are produced using group theory and hyperbolic geometry. The main results are a generic procedure to produce such tilings, and a collection of intriguing shapes and images. Furthermore, we show how to produce shapes of genus 2 and higher with a highly regular structure.
Visio-lization
Authors: Mohammed Umar , Prince Simon J. D. , Kautz Jan
Published: July 2009

Our goal is to generate novel realistic images of faces using a model trained from real examples. This model consists of two components: First we consider face images as samples from a texture with spatially varying statistics and describe this texture with a local non-parametric model. Second, we learn a parametric global model of all of the pixel values. To generate realistic faces, we combine the strengths of both approaches and condition the local non-parametric model on the global parametric model. We demonstrate that with appropriate choice of local and global models it is possible to reliably generate new realistic face images that do not correspond to any individual in the training data. We extend the model to cope with considerable intra-class variation (pose and illumination). Finally, we apply our model to editing real facial images: we demonstrate image in-painting, interactive techniques for improving synthesized images and modifying facial expressions.
Real-time hand-tracking with a color glove
Authors: Wang Robert Y. , Popović Jovan
Published: July 2009

Articulated hand-tracking systems have been widely used in virtual reality but are rarely deployed in consumer applications due to their price and complexity. In this paper, we propose an easy-to-use and inexpensive system that facilitates 3-D articulated user-input using the hands. Our approach uses a single camera to track a hand wearing an ordinary cloth glove that is imprinted with a custom pattern. The pattern is designed to simplify the pose estimation problem, allowing us to employ a nearest-neighbor approach to track hands at interactive rates. We describe several proof-of-concept applications enabled by our system that we hope will provide a foundation for new interactions in modeling, animation control and augmented reality.
SkyFinder
Authors: Tao Litian , Yuan Lu , Sun Jian
Published: July 2009

In this paper, we present SkyFinder, an interactive search system of over a half million sky images downloaded from the Internet. Using a set of automatically extracted, semanticsky attributes(category, layout, richness, horizon, etc.), the user can find a desired sky image, such as "a landscape with rich clouds at sunset" or "a whole blue sky with white clouds". The system is fully automatic and scalable. It computes all sky attributes offline, then provides an interactive online search engine. Moreover, we build a sky graph based on the sky attributes, so that the user can smoothly explore and find a path within the space of skies. We also show how our system can be used for controllable sky replacement.
Paint selection
Authors: Liu Jiangyu , Sun Jian , Shum Heung-Yeung
Published: July 2009

In this paper, we present Paint Selection, a progressive painting-based tool for local selection in images. Paint Selection facilitates users to progressively make a selection by roughly painting the object of interest using a brush. More importantly, Paint Selection is efficient enough that instant feedback can be provided to users as they drag the mouse. We demonstrate that high quality selections can be quickly and effectively "painted" on a variety of multi-megapixel images.
A visibility algorithm for converting 3D meshes into editable 2D vector graphics
Authors: Eisemann Elmar , Paris Sylvain , Durand Frédo
Published: July 2009

Artists often need to import and embellish 3D models coming from CAD-CAM into 2D vector graphics software to produce, e.g., brochures or manuals. Current automatic solutions tend to result, at best, in a 2D triangle soup and artists often have to trace over 3D renderings. We describe a method to convert 3D models into 2D layered vector illustrations that respect visibility and facilitate further editing. Our core contribution is a visibility method that can partition a mesh into large components that can be layered according to visibility. Because self-occluding objects and objects forming occlusion cycles cannot be represented by layers without being cut, we introduce a new cut algorithm that uses a graph representation of the mesh and curvature-aware geodesic distances.
Capture and modeling of non-linear heterogeneous soft tissue
Authors: Bickel Bernd , Bächer Moritz , Otaduy Miguel A. , Matusik Wojciech , Pfister Hanspeter , Gross Markus
Published: July 2009

This paper introduces a data-driven representation and modeling technique for simulating non-linear heterogeneous soft tissue. It simplifies the construction of convincing deformable models by avoiding complex selection and tuning of physical material parameters, yet retaining the richness of non-linear heterogeneous behavior. We acquire a set of example deformations of a real object, and represent each of them as a spatially varying stress-strain relationship in a finite-element model. We then model the material by non-linear interpolation of these stress-strain relationships in strain-space. Our method relies on a simple-to-build capture system and an efficient run-time simulation algorithm based on incremental loading, making it suitable for interactive computer graphics applications. We present the results of our approach for several non-linear materials and biological soft tissue, with accurate agreement of our model to the measured data.
Dark flash photography
Authors: Krishnan Dilip , Fergus Rob
Published: July 2009

Camera flashes produce intrusive bursts of light that disturb or dazzle. We present a prototype camera and flash that uses infra-red and ultra-violet light mostly outside the visible range to capture pictures in low-light conditions. This "dark" flash is at least two orders of magnitude dimmer than conventional flashes for a comparable exposure. Building on ideas from flash/no-flash photography, we capture a pair of images, one using the dark flash, other using the dim ambient illumination alone. We then exploit the correlations between images recorded at different wavelengths to denoise the ambient image and restore fine details to give a high quality result, even in very weak illumination. The processing techniques can also be used to denoise images captured with conventional cameras.
4D frequency analysis of computational cameras for depth of field extension
Authors: Levin Anat , Hasinoff Samuel W. , Green Paul , Durand Frédo , Freeman William T.
Published: July 2009

Depth of field (DOF), the range of scene depths that appear sharp in a photograph, poses a fundamental tradeoff in photography---wide apertures are important to reduce imaging noise, but they also increase defocus blur. Recent advances in computational imaging modify the acquisition process to extend the DOF through deconvolution. Because deconvolution quality is a tight function of the frequency power spectrum of the defocus kernel, designs with high spectra are desirable. In this paper we study how to design effective extended-DOF systems, and show an upper bound on the maximal power spectrum that can be achieved. We analyze defocus kernels in the 4D light field space and show that in the frequency domain, only a low-dimensional 3D manifold contributes to focus. Thus, to maximize the defocus spectrum, imaging systems should concentrate their limited energy on this manifold. We review several computational imaging systems and show either that they spend energy outside the focal manifold or do not achieve a high spectrum over the DOF. Guided by this analysis we introduce the lattice-focal lens, which concentrates energy at the low-dimensional focal manifold and achieves a higher power spectrum than previous designs. We have built a prototype lattice-focal lens and present extended depth of field results.
Interacting process classes
Authors: Goel Ankit , Roychoudhury Abhik , Thiagarajan P. S.
Published: July 2009

Many reactive control systems consist of classes of active objects involving both intraclass interactions (i.e., objects belonging to the same class interacting with each other) and interclass interactions. Such reactive control systems appear in domains such as telecommunication, transportation and avionics. In this article, we propose a modeling and simulation technique for interacting process classes. Our modeling style uses standard notations to capture behavior. In particular, the control flow of a process class is captured by a labeled transition system, unit interactions between process objects are described as
transactions
, and the structural relations are captured via class diagrams. The key feature of our approach is that our execution semantics leads to an
abstract
simulation technique which involves (i) grouping together active objects into equivalence classes according their potential futures, and (ii) keeping track of the number of objects in an equivalence class rather than their identities. Our simulation strategy is both time and memory efficient and we demonstrate this on well-studied nontrivial examples of reactive systems. We also present a case study involving a weather-update controller from NASA to demonstrate the use of our simulator for debugging realistic designs.
Verdict functions in testing with a fault domain or test hypotheses
Authors: Hierons Robert M.
Published: July 2009

In state-based testing, it is common to include verdicts within test cases, the result of the test case being the verdict reached by the test run. In addition, approaches that reason about test effectiveness or produce tests that are guaranteed to find certain classes of faults are often based on either a fault domain or a set of test hypotheses. This article considers how the presence of a fault domain or test hypotheses affects our notion of a test verdict. The analysis reveals the need for new verdicts that provide more information than the current verdicts and for verdict functions that return a verdict based on a set of test runs rather than a single test run. The concepts are illustrated in the contexts of testing from a nondeterministic finite state machine and the testing of a datatype specified using an algebraic specification language but are potentially relevant whenever fault domains or test hypotheses are used.
Programming pervasive and mobile computing applications
Authors: Mamei Marco , Zambonelli Franco
Published: July 2009

Pervasive and mobile computing call for suitable middleware and programming models to support the activities of complex software systems in dynamic network environments. In this article we present TOTA (“Tuples On The Air”), a novel middleware and programming approach for supporting adaptive context-aware activities in pervasive and mobile computing scenarios. The key idea in TOTA is to rely on spatially distributed tuples, adaptively propagated across a network on the basis of application-specific rules, for both representing contextual information and supporting uncoupled interactions between application components. TOTA promotes a simple way of programming that facilitates access to distributed information, navigation in complex environments, and the achievement of complex coordination tasks in a fully distributed and adaptive way, mostly freeing programmers and system managers from the need to take care of low-level issues related to network dynamics. This article includes both application examples to clarify concepts and performance figures to show the feasibility of the approach
Editorial
Authors: Li Zhiyuan , Pande Santosh
Published: July 2009

Publisher Note:
This Guest Editorial by Li and Pande describes a number of related articles originally intended as a special issue but which were published in earlier issues as follows:

Auerbach et al., "Low-Latency Time-Portable Real-Time Programming with Exotasks"
, appears in TECS 8(2) Article 15 DOI 10.1145/1457255.1457262

Murray et al., "Code Transformation and Instruction Set Extension"
, appears in TECS 8(4) Article 26 DOI 10.1145/1550987.1550989

Ahn and Paek, "Register Coalescing Techniques for Heterogeneous Register Architecture with Copy Sifting"
, appears in TECS 8(2) Article 16 DOI 10.1145/1457255.1457263

Yan and Zhang, "Analyzing the Worst-Case Execution Time for Instruction Caches with Prefetching"
, appears in TECS 8(1) Article 7 DOI 10.1145/1457246.1457253
Code transformation and instruction set extension
Authors: Murray Alastair C. , Bennett Richard V. , Franke Björn , Topham Nigel
Published: July 2009

The demand for flexible embedded solutions and short time-to-market has led to the development of extensible processors that allow for customization through user-defined instruction set extensions (ISEs). These are usually identified from plain C sources. In this article, we propose a combined exploration of code transformations and ISE identification. The resulting performance of such a combination has been measured on two benchmark suites. Our results demonstrate that combined code transformations and ISEs can yield average performance improvements of 49%. This outperforms ISEs when applied in isolation, and in extreme cases yields a speed-up of 2.85.
An online blog reading system by topic clustering and personalized ranking
Authors: Li Xin , Yan Jun , Fan Weiguo , Liu Ning , Yan Shuicheng , Chen Zheng
Published: July 2009

There is an increasing number of people reading, writing, and commenting on blogs. According to a recent survey made by Technorati, there are about 75,000 new blogs and 1.2 million new posts everyday. However, it is difficult and time consuming for a blog reader to find the most interesting posts in the huge and dynamic blog world. In this article, an online Personalized Blog Reader (PBR) system is proposed, which facilitates blog readers in browsing the coolest and newest blog posts of their interests by automatically clustering the most relevant stories. PBR aims to make a user's potential favorite topics always ranked higher than those nonfavorite ones. This is accomplished in the following steps. First, the system collects and provides a unified incremental index of posts coming from different blogs. Then, an incremental clustering algorithm with a flexible half-bounded window of observation is proposed to satisfy the requirements of online processing. It learns people's personalized reading preferences to present a user with a final reading list. The experimental results show that the proposed incremental clustering algorithm is effective and efficient, and the personalization of the PBR performs well.