bluuebunny/crossref_metadata_2025 huggingface dataset:
Resistance Analysis of the Hepatitis C Virus NS5A Inhibitor BMS-790052 in an
In Vitro
Replicon System
Authors: Fridell Robert A. , Qiu Dike , Wang Chunfu , Valera Lourdes , Gao Min
Published: June 2010

BMS-790052 is the most potent hepatitis C virus (HCV) inhibitor reported to date, with 50% effective concentrations (EC
50
s) of ≤50 pM against genotype 1 replicons. This exceptional potency translated to rapid viral load declines in a phase I clinical study. By targeting NS5A, BMS-790052 is distinct from most HCV inhibitors in clinical evaluation. As an initial step toward correlating
in vitro
and
in vivo
resistances, multiple cell lines and selective pressures were used to identify BMS-790052-resistant variants in genotype 1 replicons. Similarities and differences were observed between genotypes 1a and 1b. For genotype 1b, L31F/V, P32L, and Y93H/N were identified as primary resistance mutations. L23F, R30Q, and P58S acted as secondary resistance substitutions, enhancing the resistance of primary mutations but themselves not conferring resistance. For genotype 1a, more sites of resistance were identified, and substitutions at these sites (M28T, Q30E/H/R, L31M/V, P32L, and Y93C/H/N) conferred higher levels of resistance. For both subtypes, combining two resistance mutations markedly decreased inhibitor susceptibility. Selection studies with a 1b/1a hybrid replicon highlighted the importance of the NS5A N-terminal region in determining genotype-specific inhibitor responses. As single mutations, Q30E and Y93N in genotype 1a conferred the highest levels of resistance. For genotype 1b, BMS-790052 retained subnanomolar potency against all variants with single amino acid substitutions, suggesting that multiple mutations will likely be required for significant
in vivo
resistance in this genetic background. Importantly, BMS-790052-resistant variants remained fully sensitive to alpha interferon and small-molecule inhibitors of HCV protease and polymerase.
Impact of Cotrimoxazole on Carriage and Antibiotic Resistance of
Streptococcus pneumoniae
and
Haemophilus influenzae
in HIV-Infected Children in Zambia
Authors: Mwenya Darlington M. , Charalambous Bambos M. , Phillips Patrick P. J. , Mwansa James C. L. , Batt Sarah L. , Nunn Andrew J. , Walker Sarah , Gibb Diana M. , Gillespie Stephen H.
Published: June 2010

This is a substudy of a larger randomized controlled trial on HIV-infected Zambian children, which revealed that cotrimoxazole prophylaxis reduced morbidity and mortality despite a background of high cotrimoxazole resistance. The impact of cotrimoxazole on the carriage and antibiotic resistance of
Streptococcus pneumoniae
and
Haemophilus influenzae
as major causes of childhood mortality in HIV-infected children was investigated since these are unclear. Representative nasopharyngeal swabs were taken prior to randomization for 181 of 534 children (92 on cotrimoxazole and 89 on placebo). Bacterial identification and antibiotic susceptibility were performed by routine methods. Due to reduced mortality, prophylactic cotrimoxazole increased the median time from randomization to the last specimen from 48 to 56 months (
P
= 0.001). The carriage of
H. influenzae
was unaltered by cotrimoxazole. Carriage of
S. pneumoniae
increased slightly in both arms but was not statistically significant in the placebo arm. In
S. pneumoniae
switching between carriage and no carriage in consecutive pairs of samples was unaffected by cotrimoxazole (
P
= 0.18) with a suggestion that the probability of remaining carriage free was lower (
P
= 0.10). In
H. influenzae
cotrimoxazole decreased switching from carriage to no carriage (
P
= 0.02). Cotrimoxazole resistance levels were higher in postbaseline samples in the cotrimoxazole arm than in the placebo arm (
S. pneumoniae
,
P
< 0.0001;
H. influenzae
,
P
= 0.005). Cotrimoxazole decreased switching from cotrimoxazole resistance to cotrimoxazole sensitivity in
S. pneumoniae
(
P
= 0.002) and reduced the chance of
H. influenzae
remaining cotrimoxazole sensitive (
P
= 0.05). No associations were observed between the percentage of CD4 (CD4%), the change in CD4% from baseline, child age at date of specimen, child gender, or sampling month with carriage of either pathogen.
Serum and Cerebrospinal Fluid Levels of Colistin in Pediatric Patients
Authors: Antachopoulos Charalampos , Karvanen Matti , Iosifidis Elias , Jansson Britt , Plachouras Diamantis , Cars Otto , Roilides Emmanuel
Published: June 2010

Using a liquid chromatography-tandem mass spectrometry method, the serum and cerebrospinal fluid (CSF) concentrations of colistin were determined in patients aged 1 months to 14 years receiving intravenous colistimethate sodium (60,000 to 225,000 IU/kg of body weight/day). Only in one of five courses studied (a 14-year-old receiving 225,000 IU/kg/day) did serum concentrations exceed the 2 μg/ml CLSI/EUCAST breakpoint defining susceptibility to colistin for
Pseudomonas
and
Acinetobacter.
CSF colistin concentrations were <0.2 μg/ml but increased in the presence of meningitis (∼0.5 μg/ml or 34 to 67% of serum levels).
A Pathoadaptive Deletion in an EnteroaggregativeEscherichia coliOutbreak Strain Enhances Virulence in aCaenorhabditis elegansModel
Authors: Hwang Jennifer , Mattei Lisa M. , VanArendonk Laura G. , Meneely Philip M. , Okeke Iruka N.
Published: June 2010

EnteroaggregativeEscherichia coli(EAEC) strains are important diarrheal pathogens. EAEC strains are defined by their characteristic stacked-brick pattern of adherence to epithelial cells but show heterogeneous virulence and have different combinations of adhesin and toxin genes. Pathoadaptive deletions in the lysine decarboxylase (cad) genes have been noted among hypervirulentE. colisubtypes ofShigellaand enterohemorrhagicE. coli. To test the hypothesis thatcaddeletions might account for heterogeneity in EAEC virulence, we developed aCaenorhabditis eleganspathogenesis model. Well-characterized EAEC strains were shown to colonize and killC. elegans, and differences in virulence could be measured quantitatively. Of 49 EAEC strains screened for lysine decarboxylase activity, 3 tested negative. Most notable is isolate 101-1, which was recovered in Japan, from the largest documented EAEC outbreak. EAEC strain 101-1 was unable to decarboxylate lysinein vitrodue to deletions incadAandcadC, which, respectively, encode lysine decarboxylase and a transcriptional activator of thecadABgenes. Strain 101-1 was significantly more lethal toC. elegansthan control strain OP50. Lethality was attenuated when the lysine decarboxylase defect was complemented from a multicopy plasmid and in single copy. In addition, restoring lysine decarboxylase function produced derivatives of 101-1 deficient in aggregative adherence to cultured human epithelial cells. Lysine decarboxylase inactivation is pathoadapative in an important EAEC outbreak strain, and deletion ofcadgenes could produce hypervirulent EAEC lineages in the future. These results suggest that loss, as well as gain, of genetic material can account for heterogeneous virulence among EAEC strains.
Transforming Growth Factor β and CD25 Are Important for Controlling Systemic Dissemination followingYersiniaenterocoliticaInfection of the Gut
Authors: Zhong Youmin , Cantwell Angelene , Dube Peter H.
Published: June 2010

Infection of the gut by invasive bacterial pathogens leads to robust inflammatory responses that if left unchecked can lead to autoimmune disease and other sequelae. How the immune system controls inflammation and limits collateral damage to the host during acute bacterial infection is poorly understood. Here, we report that antibody-mediated neutralization of transforming growth factor β (TGF-β) prior to infection with the model enteric pathogenYersinia enterocoliticareduces the mean time to death by 1 day (P= 0.001), leads to rapid colonization of the liver and lung, and is associated with exacerbation of inflammatory histopathology. DuringYersinia enterocoliticainfection CD4+cells are the source ofde novoTGF-β transcription in the Peyer's patches, mesenteric lymph nodes, and spleen. Correspondingly there is both antigen-specific and -independent expansion of CD4+CD25+Foxp3+and TGF-β+T-regulatory cells (T-regs) afterYersiniainfection that is reduced in ovalbumin T-cell receptor-restricted OT-II mice. Functional inactivation of CD25 by anti-CD25 treatment results in more rapid death, dissemination of the bacteria to the liver and lungs, and exacerbated inflammatory histopathology, similar to what is seen during TGF-β neutralization. Altogether, these data suggest that TGF-β produced by T-regs is important in restricting bacteria during the acute phase of invasive bacterial infection of the gut. These data expand the roles of T-regs to include tempering inflammation during acute infection in addition to the well-established roles of T-regs in chronic infection, control of immune homeostasis, and autoimmune disease.
Interleukin-17A during Local and SystemicStaphylococcus aureus-Induced Arthritis in Mice
Authors: Henningsson Louise , Jirholt Pernilla , Lindholm Catharina , Eneljung Tove , Silverpil Elin , Iwakura Yoichiro , Linden Anders , Gjertsson Inger
Published: June 2010

Staphylococcus aureusis one of the dominant pathogens that induce septic arthritis in immunocompromised hosts, e.g., patients suffering from rheumatoid arthritis treated with immunosuppressive drugs.S. aureus-induced arthritis leads to severe joint destruction and high mortality despite antibiotic treatment. Recently, interleukin-17A (IL-17A) has been discovered to be an important mediator of aseptic arthritis both in mice and humans, but its function inS. aureus-induced arthritis is largely unknown. Here, we investigated the role of IL-17A in host defense against arthritis following systemic and localS. aureusinfectionin vivo. IL-17A knockout mice and wild-type mice were inoculated systemically (intravenously) or locally (intra-articularly) withS. aureus. During systemic infection, IL-17A knockout mice lost significantly more weight than the wild-type mice did, but no differences were found in the mortality rate. The absence of IL-17A had no impact on clinical arthritis development but led to increased histopathological erosivity late during systemicS. aureusinfection. Bacterial clearance in kidneys was increased in IL-17A knockout mice compared to the level in wild-type mice only 1 day after bacterial inoculation. During systemicS. aureusinfection, serum IL-17F protein levels and mRNA levels in the lymph nodes were elevated in the IL-17A knockout mice compared to the level in wild-type mice. In contrast to systemic infection, the IL-17A knockout mice had increased synovitis and erosions and locally decreased clearance of bacteria 3 days after local bacterial inoculation. On the basis of these findings, we suggest that IL-17A is more important in local host defense than in systemic host defense againstS. aureus-induced arthritis.
Heterogeneity in Search Strategies among Cochrane Acupuncture Reviews: Is There Room for Improvement?
Authors: Lui Steve , Smith Erica J , Terplan Mishka
Published: June 2010

Objective

Given the international focus and rigorous literature searches employed in Cochrane systematic reviews, this study was undertaken to evaluate strategies employed in Cochrane reviews and protocols assessing acupuncture as a primary or secondary intervention.

Methods

The Cochrane Collaboration of systematic reviews was searched in February 2009 for all reviews and protocols including information on acupuncture. Information was abstracted from all retrieved articles on review status, type and number of English and Chinese language databases searched, participation of at least one Chinese speaking author and language restriction. Frequencies were calculated and bivariate analyses were performed stratifying on interventions of interest to assess differences in search strategy techniques, language restrictions and results.

Results

The search retrieved 68 titles, including 48 completed reviews, 17 protocols and three previously withdrawn titles. Acupuncture was the primary intervention of interest in 44/65 (67.7%) of the retrieved reviews and protocols. While all articles searched at least one English language database, only 26/65 (40.0%) articles searched Chinese language databases. Significantly more articles where acupuncture was the primary intervention of interest searched Chinese language databases (53% vs 9%, p<0.01). Inconclusive findings as to the effectiveness of acupuncture were found in 28/48 (58.3%) of all completed reviews; this type of finding was more common in reviews which did not search any Chinese language databases.

Conclusions

It is important for reviews assessing the effectiveness of acupuncture to search Chinese language databases. The Cochrane Collaboration should develop specific criteria for Chinese language search strategies to ensure the continued publication of high-quality reviews.
Allergic and non-allergic rhinitis in swimmers: clinical and cytological aspects
Authors: Gelardi Matteo , Ventura Maria Teresa , Fiorella Raffaele , Fiorella Maria Luisa , Russo Cosimo , Candreva Teresa , Carretta Antonella , Passalacqua Giovanni
Published: June 2010

Background

Rhinitis, either allergic or non-allergic, is frequent in athletes, particularly in swimmers. In this latter case, exposure to chlorine in swimming pools seems to play a relevant role, since it can exacerbate a pre-existing allergic rhinitis (AR) or produce a non-specific irritation. The aim of this study was to detail the clinical and cytological characteristics of rhinitis in swimmers, and to assess the possible role of chlorine-induced symptoms.

Methods

Elite swimmers with rhinitis symptoms underwent a complete diagnostic work-up, including allergy testing, nasal cytology and anterior rhinomanometry. Those evaluations were repeated after 1 month of use of a nasal clip during swimming. A matched group of asymptomatic swimmers was also studied. A total of 74 swimmers (54 symptomatic and 20 controls), with an age range of 9–21 years, were studied. In the control group, only mild and non-specific findings were observed, and only two had a positive skin test.

Results

In the symptomatic group, 24 (44%) had AR, and 19 (35%) had a predominant neutrophilic inflammation. The use of a nose clip reduced cellular infiltration and nasal resistances only in the subjects with neutrophilic rhinitis, whereas a clinical improvement was seen also in AR.

Conclusion

A neutrophilic rhinitis occurs in a large proportion of swimmers. This seems to be irritative in its nature and can be prevented by avoiding the direct contact with chlorinated water.
A comparison of two treatment protocols in the management of exercise-associated postural hypotension: a randomised clinical trial
Authors: Anley Cameron , Noakes Timothy , Collins Malcolm , Schwellnus Martin P
Published: June 2010

Objective

To investigate which of two commonly used treatment protocols for exercise-associated postural hypotension (EAPH) resulted in earlier discharge from the medical facility.

Methods

This randomised clinical field trial was undertaken at two Ironman Triathlon competitions and one ultra-distance footrace. All collapsed athletes admitted to the medical facilities were considered for the trial. Following clinical assessment and special investigations to confirm the diagnosis of EAPH, 28 athletes were randomly assigned to an oral fluid and Trendelenburg position (OT=14) or an intravenous fluid (IV=14) treatment group. Following admission fluid intake was recorded, and all athletes were assessed clinically (blood pressure, heart rate, level of consciousness) every 15 min until discharge criteria were met. The main measure of outcome was the time to discharge (min).

Results

On admission, subjects in the OT and IV groups were similar with respect to age, systolic blood pressure, heart rate and serum sodium concentration. There were no significant differences in heart rate, systolic and diastolic blood pressure between groups and over time until discharge. The fluid intake during the treatment period was significantly greater in the IV group (IV 1045±185 ml, OT 204±149 ml; p<0.001). The average time to discharge for the OT group (58±23 min) was similar to that of the IV group (52.5±18 min; p=0.47).

Conclusion

Endurance athletes with EAPH can be treated effectively using the Trendelenburg position and oral fluids and the administration of intravenous fluids does not reduce the time to discharge. The findings of this study support the hypothesis that EAPH is a result of venous pooling due to peripheral vasodilatation, rather than dehydration.
Acceptability of offering financial incentives to achieve medication adherence in patients with severe mental illness: a focus group study: Figure 1
Authors: Priebe Stefan , Sinclair Julia , Burton Alexandra , Marougka Stamatina , Larsen John , Firn Mike , Ashcroft Richard
Published: June 2010

Background

Offering financial incentives to achieve medication adherence in patients with severe mental illness is controversial.

Aims

To explore the views of different stakeholders on the ethical acceptability of the practice.

Method

Focus group study consisting of 25 groups with different stakeholders.

Results

Eleven themes dominated the discussions and fell into four categories: (1) ‘wider concerns’, including the value of medication, source of funding, how patients would use the money, and a presumed government agenda behind the idea; (2) ‘problems requiring clear policies’, comprising of practicalities and assurance that incentives are only one part of a tool kit; (3) ‘challenges for research and experience’, including effectiveness, the possibility of perverse incentives, and impact on the therapeutic relationship; (4) ‘inherent dilemmas’ around fairness and potential coercion.

Conclusions

The use of financial incentives is likely to raise similar concerns in most stakeholders, only some of which can be addressed by empirical research and clear policies.
NONCOMMUTATIVE THERMOFIELD DYNAMICS
Authors: COSTA MARCELO L. , QUEIROZ AMILCAR R. , SANTANA ADEMIR E.
Published: June 2010

The real-time operator formalism for thermal quantum field theories, thermofield dynamics, is formulated in terms of a path-integral approach in noncommutative spaces. As an application, the two-point function for a thermal noncommutative λϕ4 theory is derived at the one-loop level. The effect of temperature and the noncommutative parameter, competing with one another, is analyzed.
A PERSONALIZED IMAGE RETRIEVAL BASED ON USER INTEREST MODEL
Authors: ZHANG JING , ZHUO LI , SHEN LANSUN , HE LIN
Published: June 2010

In order to narrow the semantic gap, user interest model plays an important role in personalized image retrieval. A novel personalized image retrieval approach based on user interest model is proposed in this study. User interest model is developed on the basis of short-tem and long-term interests. (1) Short-term interests are represented by collecting visual and semantic features. Visual features are collected by MARS relevance feedback. Semantic features are constructed by building a mapping from image low-level visual features to high-level semantic features on the basis of SVM. (2) Long-term interests are inferred by inference engine from the collected short-term interests. Long-term visual features are collected by the nonlinear gradual forgetting interest inference algorithm and semantic features are obtained by clustering algorithm. After applying to image retrieval, experimental results show that the average recall/precision is significantly improved and a better user satisfaction rate is achieved as well. Furthermore, it demonstrates our model can be efficiently adapted to user interests and matches personalized image retrieval.
EXISTENCE OF GUIDED CYLINDRICAL TM-MODES IN AN INHOMOGENEOUS SELF-FOCUSING DIELECTRIC
Authors: STUART C. A. , ZHOU HUAN-SONG
Published: June 2010

We consider an eigenvalue problem for a certain type of quasi-linear second-order differential equation on the interval (0, ∞). Using an appropriate version of the mountain pass theorem, we establish the existence of a positive solution in [Formula: see text] for a range of values of the eigenvalue. It is shown that these solutions generate solutions of Maxwell's equations having the form of guided travelling waves propagating through a self-focusing dielectric. Motivated by models of optical fibres, the refractive index of the dielectric has an axial symmetry but may vary with distance for the axis. Previous existence results for this problem deal only with the homogeneous case.
THE REISSNER–MINDLIN PLATE IS THE Γ-LIMIT OF COSSERAT ELASTICITY
Authors: NEFF PATRIZIO , HONG KWON-IL , JEONG JENA
Published: June 2010

The linear Reissner–Mindlin membrane-bending plate model is the rigourous Γ-limit for zero thickness of a linear isotropic Cosserat bulk model with symmetric curvature. For this result we use the natural nonlinear scaling for the displacements u and the linear scaling for the infinitesimal microrotations Ā ∈ 𝔰𝔬(3). We also provide formal calculations for other combinations of scalings by retrieving other plate models previously proposed in the literature by formal asymptotic methods as corresponding Γ-limits. No boundary conditions on the microrotations are prescribed.
EXACT PRICING ASYMPTOTICS OF INVESTMENT-GRADE TRANCHES OF SYNTHETIC CDO'S: A LARGE HOMOGENEOUS POOL
Authors: SOWERS RICHARD B.
Published: June 2010

We use the theory of large deviations to study the pricing of investment-grade tranches of synthetic CDO's. In this paper, we consider a simplified model which will allow us to introduce some of the concepts and calculations.
A MULTILEVEL APPROACH TO SOLVING THE BLACK–SCHOLES EQUATION
Authors: MORRIS HEDLEY , LIMON ALFONSO
Published: June 2010

In this manuscript, we develop a multilevel framework for the pricing of a European call option based on multiresolution techniques. In this approach, the Black–Scholes equation is transformed via finite differences into a system of linear equations, where the form of the implicit operator is used to construct coarse grid projectors. The reduction of the computational resource is achieved by truncating small wavelet coefficients. However, because traditional wavelets fail to prevent oscillations from developing in the Greeks, a multilevel approach is used to retain smoothness in Gamma by incorporating derivative information into the multiresolution analysis.
REGIME-SWITCHING RECOMBINING TREE FOR OPTION PRICING
Authors: LIU R. H.
Published: June 2010

In this paper we develop an efficient tree approach for option pricing when the underlying asset price follows a regime-switching model. The tree grows only linearly as the number of time steps increases. Thus it enables us to use large number of time steps to compute accurate prices for both European and American options. We present conditions that guarantee the positivity of branch probabilities. We numerically test the sensitivity of option prices to the choice of a key parameter for tree construction. As an interesting application, we develop a regime-switching model to approximate the Heston's stochastic volatility model and then employ the tree approach to approximate the option prices. Numerical results are provided and compared.
ASYMPTOTIC ANALYSIS FOR A VLASOV–NAVIER–STOKES SYSTEM IN A BOUNDED DOMAIN
Authors: EL GHANI NAJOUA
Published: June 2010

This article is devoted to the asymptotic analysis of a Vlasov–Navier–Stokes system in dimension two, and treat general initial data with finite mass, energy and entropy. The limit problem is the Navier–Stokes system with non-constant density. The convergence result is proved in a bounded domain of ℝ2with a homogeneous Dirichlet boundary condition on the fluid velocity field and Maxwell boundary condition on the kinetic distribution function, while the proof relies on a relative entropy method.
SYSTEMS OF HYPERBOLIC CONSERVATION LAWS WITH PRESCRIBED EIGENCURVES
Authors: JENSSEN HELGE KRISTIAN , KOGAN IRINA A.
Published: June 2010

We study the problem of constructing systems of hyperbolic conservation laws in one space dimension with prescribed eigencurves, i.e. the eigenvector fields of the Jacobian of the flux are given. We formulate this as a typically overdetermined system of equations for the eigenvalues-to-be. Equivalent formulations in terms of differential and algebraic-differential equations are considered. The resulting equations are then analyzed using appropriate integrability theorems (Frobenius, Darboux and Cartan–Kähler). We give a complete analysis of the possible scenarios, including examples, for systems of three equations. As an application we characterize conservative systems with the same eigencurves as the Euler system for 1-dimensional compressible gas dynamics. The case of general rich systems of any size (i.e. when the given eigenvector fields are pairwise in involution; this includes all systems of two equations) is completely resolved and we consider various examples in this class.
ON THE DIMENSION OF THE SPACE OF CUSP FORMS OF OCTAHEDRAL TYPE
Authors: GANGULY SATADAL
Published: June 2010

For a prime q ≡ 3 ( mod 4) and the character [Formula: see text], we consider the subspace of the space of holomorphic cusp forms of weight one, level q and character χ that is spanned by forms that correspond to Galois representations of octahedral type. We prove that this subspace has dimension bounded by [Formula: see text] upto multiplication by a constant that depends only on ε.
ABELIAN SURFACES WITH SUPERSINGULAR GOOD REDUCTION AND NON-SEMISIMPLE TATE MODULE
Authors: VOLKOV MAJA
Published: June 2010

We show the existence of abelian surfaces [Formula: see text] over ℚp having good reduction with supersingular special fiber whose associated p-adic Galois module [Formula: see text] is not semisimple.
SMALL VALUE ESTIMATES FOR THE ADDITIVE GROUP
Authors: ROY DAMIEN
Published: June 2010

We generalize Gel'fond's criterion for algebraic independence to the context of a sequence of polynomials whose first derivatives take small values on large subsets of a fixed subgroup of ℂ, instead of just one point (one extension deals with a subgroup of ℂ×).
RAMANUJAN CONGRUENCES FOR A CLASS OF ETA QUOTIENTS
Authors: SINICK JONAH
Published: June 2010

We consider a class of generating functions analogous to the generating function of the partition function and establish a bound on the primes ℓ for which their coefficients c(n) obey congruences of the form c(ℓn + a) ≡ 0 ( mod ℓ). We apply this result to obtain a complete characterization of the congruences of the same form that the sequences cN(n) satisfy, where cN(n) is defined by [Formula: see text]. This last result answers a question of H.-C. Chan.
BERNOULLI NUMBERS AND CONGRUENCES FOR HARMONIC SUMS
Authors: XIA BINZHOU , CAI TIANXIN
Published: June 2010

Zhao established the following harmonic congruence for prime p > 3: [Formula: see text] In this note, the authors improve it to the following congruence for prime p > 5: [Formula: see text] Meanwhile, they also improve a generalization of Zhao's congruence and extend Eisenstein's congruence.
THE FIRST NEGATIVE HECKE EIGENVALUE OF GENUS 2 SIEGEL CUSPFORMS WITH LEVEL N ≥ 1
Authors: BROWN JIM
Published: June 2010

In this short paper, we extend results of Kohnen and Sengupta on the sign of eigenvalues of Siegel cuspforms. We show that their bound for the first negative Hecke eigenvalue of a genus 2 Siegel cuspform of level 1 extends to the case of level N > 1. We also discuss the signs of Hecke eigenvalues of CAP forms.
EXPONENTIAL SUMS OVER PRIMES IN RESIDUE CLASSES
Authors: MAIER H. , SANKARANARAYANAN A.
Published: June 2010

We specialize a problem studied by Elliott, the behavior of arbitrary sequences ap of complex numbers on residue classes to prime moduli to the case ap = e(αp). For these special cases, we obtain under certain additional conditions improvements on Elliott's results.
Using topic themes for multi-document summarization
Authors: Harabagiu Sanda , Lacatusu Finley
Published: June 2010

The problem of using topic representations for multidocument summarization (MDS) has received considerable attention recently. Several topic representations have been employed for producing informative and coherent summaries. In this article, we describe five previously known topic representations and introduce two novel representations of topics based on topic themes. We present eight different methods of generating multidocument summaries and evaluate each of these methods on a large set of topics used in past DUC workshops. Our evaluation results show a significant improvement in the quality of summaries based on topic themes over MDS methods that use other alternative topic representations.
STEvent
Authors: Lauw Hady W. , Lim Ee-Peng , Pang Hweehwa , Tan Teck-Tim
Published: June 2010

Spatio-temporal data concerning the movement of individuals over space and time contains latent information on the associations among these individuals. Sources of spatio-temporal data include usage logs of mobile and Internet technologies. This article defines a spatio-temporal event by the co-occurrences among individuals that indicate potential associations among them. Each spatio-temporal event is assigned a weight based on the precision and uniqueness of the event. By aggregating the weights of events relating two individuals, we can determine the strength of association between them. We conduct extensive experimentation to investigate both the efficacy of the proposed model as well as the computational complexity of the proposed algorithms. Experimental results on three real-life spatio-temporal datasets cross-validate each other, lending greater confidence on the reliability of our proposed model.
A Course on Reconfigurable Processors
Authors: Shoufan Abdulhadi , Huss Sorin A.
Published: June 2010

Reconfigurable computing is an established field in computer science. Teaching this field to computer science students demands special attention due to limited student experience in electronics and digital system design. This article presents a compact course on reconfigurable processors, which was offered at the Technische Universität Darmstadt, and is intended for instructors aiming to introduce a new course in reconfigurable computing. Therefore, a detailed description of the course structure and content is provided. In contrast to courses on digital system design, which use FPGAs as a case platform, our course places this platform at the center of its focus and highlights its features as a basis for reconfigurable computing. Both declarative knowledge and functioning knowledge are considered in defining learning outcomes based on a novel What-Why-How Model. Lab activities were designated to deepen the functioning knowledge. The written exam is aligned to learning outcomes and shows that most students acquired the intended outcomes.
An explicit universal cycle for the (
n
-1)-permutations of an
n
-set
Authors: Ruskey Frank , Williams Aaron
Published: June 2010

We show how to construct an
explicit
Hamilton cycle in the directed Cayley graph C
→
({σ

n

, σ

n
-1

}: S

n

), where σ

k

is the rotation (1 2 …
k
). The existence of such cycles was shown by Jackson [1996] but the proof only shows that a certain directed graph is Eulerian, and Knuth [2005] asks for an explicit construction. We show that a simple recursion describes our Hamilton cycle and that the cycle can be generated by an iterative algorithm that uses
O
(
n
) space. Moreover, the algorithm produces each successive edge of the cycle in constant time; such algorithms are said to be
loopless
. Finally, our Hamilton cycle can be used to construct an explicit universal cycle for the (
n
-1)-permutations of a
n
-set, or as the basis of an efficient algorithm for generating every
n
-permutation of an
n
-set within a circular array or linked list.
An approximation algorithm for the maximum leaf spanning arborescence problem
Authors: Drescher Matthew , Vetta Adrian
Published: June 2010

We present an
O
(√opt)-approximation algorithm for the maximum leaf spanning arborescence problem, where opt is the number of leaves in an optimal spanning arborescence. The result is based upon an
O
(1)-approximation algorithm for a special class of directed graphs called willows. Incorporating the method for willow graphs as a subroutine in a local improvement algorithm gives the bound for general directed graphs.
Achieving anonymity via clustering
Authors: Aggarwal Gagan , Panigrahy Rina , Feder Tomás , Thomas Dilys , Kenthapadi Krishnaram , Khuller Samir , Zhu An
Published: June 2010

Publishing data for analysis from a table containing personal records, while maintaining individual privacy, is a problem of increasing importance today. The traditional approach of deidentifying records is to remove identifying fields such as social security number, name, etc. However, recent research has shown that a large fraction of the U.S. population can be identified using nonkey attributes (called quasi-identifiers) such as date of birth, gender, and zip code. The
k
-anonymity model protects privacy via requiring that nonkey attributes that leak information are suppressed or generalized so that, for every record in the modified table, there are at least
k
−1 other records having exactly the same values for quasi-identifiers. We propose a new method for anonymizing data records, where quasi-identifiers of data records are first clustered and then cluster centers are published. To ensure privacy of the data records, we impose the constraint that each cluster must contain no fewer than a prespecified number of data records. This technique is more general since we have a much larger choice for cluster centers than
k
-anonymity. In many cases, it lets us release a lot more information without compromising privacy. We also provide constant factor approximation algorithms to come up with such a clustering. This is the first set of algorithms for the anonymization problem where the performance is independent of the anonymity parameter
k
. We further observe that a few outlier points can significantly increase the cost of anonymization. Hence, we extend our algorithms to allow an ϵ fraction of points to remain unclustered, that is, deleted from the anonymized publication. Thus, by not releasing a small fraction of the database records, we can ensure that the data published for analysis has less distortion and hence is more useful. Our approximation algorithms for new clustering objectives are of independent interest and could be applicable in other clustering scenarios as well.
Approximating the distance to monotonicity in high dimensions
Authors: Fattal Shahar , Ron Dana
Published: June 2010

In this article we study the problem of approximating the distance of a function
f
: [
n
]

d

→
R
to monotonicity where [
n
] = {1,…,
n
} and
R
is some fully ordered range. Namely, we are interested in randomized sublinear algorithms that approximate the Hamming distance between a given function and the closest monotone function. We allow both an additive error, parameterized by δ, and a multiplicative error.

Previous work on distance approximation to monotonicity focused on the one-dimensional case and the only explicit extension to higher dimensions was with a multiplicative approximation factor exponential in the dimension
d
. Building on Goldreich et al. [2000] and Dodis et al. [1999], in which there are better implicit results for the case
n
=2, we describe a reduction from the case of functions over the
d
-dimensional hypercube [
n
]

d

to the case of functions over the
k
-dimensional hypercube [
n
]

k

, where 1≤
k
≤
d
. The quality of estimation that this reduction provides is linear in ⌈
d
/
k
⌉ and logarithmic in the size of the range |
R
| (if the range is infinite or just very large, then log |
R
| can be replaced by
d
log
n
). Using this reduction and a known distance approximation algorithm for the one-dimensional case, we obtain a distance approximation algorithm for functions over the
d
-dimensional hypercube, with any range
R
, which has a multiplicative approximation factor of
O
(
d
log |
R
|).

For the case of a binary range, we present algorithms for distance approximation to monotonicity of functions over one dimension, two dimensions, and the
k
-dimensional hypercube (for any
k
≥ 1). Applying these algorithms and the reduction described before, we obtain a variety of distance approximation algorithms for Boolean functions over the
d
-dimensional hypercube which suggest a trade-off between quality of estimation and efficiency of computation. In particular, the multiplicative error ranges between
O
(
d
) and
O
(1).
Ordering by weighted number of wins gives a good ranking for weighted tournaments
Authors: Coppersmith Don , Fleischer Lisa K. , Rurda Atri
Published: June 2010

We consider the following simple algorithm for feedback arc set problem in weighted tournaments: order the vertices by their weighted indegrees. We show that this algorithm has an approximation guarantee of 5 if the weights satisfy
probability constraints
(for any pair of vertices
u
and
v
,
w

uv

+
w

vu

=1). Special cases of the feedback arc set problem in such weighted tournaments include the feedback arc set problem in unweighted tournaments and rank aggregation. To complement the upper bound, for any constant ϵ>0, we exhibit an infinite family of (unweighted) tournaments for which the aforesaid algorithm (
irrespective
of how ties are broken) has an approximation ratio of 5-ϵ.
Approximating corridors and tours via restriction and relaxation techniques
Authors: Gonzalez-Gutierrez Arturo , Gonzalez Teofilo F.
Published: June 2010

Given a rectangular boundary partitioned into rectangles, the Minimum-Length Corridor (MLC-R) problem consists of finding a corridor of least total length. A corridor is a set of connected line segments, each of which must lie along the line segments that form the rectangular boundary and/or the boundary of the rectangles, and must include at least one point from the boundary of every rectangle and from the rectangular boundary. The MLC-R problem is known to be NP-hard. We present the first polynomial-time constant ratio approximation algorithm for the MLC-R and MLC

k

problems. The MLC

k

problem is a generalization of the MLC-R problem where the rectangles are rectilinear
c
-gons, for
c
≤
k
and
k
is a constant. We also present the first polynomial-time constant ratio approximation algorithm for the Group Traveling Salesperson Problem (GTSP) for a rectangular boundary partitioned into rectilinear
c
-gons as in the MLC

k

problem. Our algorithms are based on the restriction and relaxation approximation techniques.
Storage research in industry and universities
Authors: Thomasian Alexander
Published: June 2010

We review activities at universities and industrial research centers in the storage area, but also briefly mention topics such as processor design, operating systems, databases, and performance analysis. Our starting point is the Berkeley RAID proposal and the associated taxonomy two decades ago. Important research groups are listed and key researchers are identified. We pay special attention to faculty/student relationships, listing PhD theses and articles related to storage. We also describe innovative storage products and the companies behind them. This paper complements author's "Publications in Storage and Systems", ACM CAN, Sept. 2009.
Resources instead of cores?
Authors: Matthes Wolfgang
Published: June 2010

Mapping conventional applications to multiple cores is a difficult problem. To provide a general solution, it is proposed to abandon the very concept of processor cores and to populate the silicon real estate with less complex control and operation units, designated as resources. A hardware-software API is described that can put into effect a practically unlimited number of such resources and that allows for completely describing and exploiting the inherent parallelism of the application problems. The paper introduces the principles of operation, discusses problems of feasibility and outlines the basic philosophy behind the approach. The proposed principles may lead to:

Instruction set architectures which can cope with a transfinite number of hardware resources.

Processor circuits containing resources of intermediate granularity and appropriately optimized interconnects.

Considerable reduction of power consumption during operation at full speed.

.
Unit normalization of multinomials over Gaussian integers
Authors: Stoutemyer David R.
Published: June 2010

Polynomials over the Gaussian integers Z[
i
] are a unique factorization domain, and the units in Z[
i
] are 1, -1, i and --
i
. To implement the advantageous uniqueness, we might have to factor one of these units out of some multinomial factors to make all of the factors unit normal. Not doing so can lead to unnecessarily complicated results, disastrous unrecognized division by 0, and lost opportunities to obtain closed-form integrals, sums, limits, equation solutions, etc. For example, the default simplification of at least two major computer algebra systems don't recognize that the linear factors in the numerator and denominator of the following ratio are proportional, hence do not simplify the ratio to 1: --
i
((1 +
i
)
z
+
i
) / (1 --
i
)
z
+ 1 →1.

Unlike polynomials over the integers or rational numbers, the literature doesn't appear to address unit normalization over the Gaussian integers. Therefore this note proposes two alternative definitions. They are easy to implement, execute quickly, and can't greatly increase the bulk of an expression. Consequently they are good candidates for inclusion in the default simplification of every computer algebra system.
Effcient programming techniques for the SACLIB computer algebra library
Authors: Richardson David
Published: June 2010

This dissertation describes three contributions to the SACLIB computer algebra library. Using generic programming we specify the Recursively Fixed Iterator and the Structure Protecting Iterator concepts. We prove that models of these concepts cannot leak or double delete resources. Through template metaprogramming, we implement models of these concepts that provide this memory safety at compile-time and without any run-time overhead. Using aspect oriented programming, we allow unit and regression tests to be automatically obtained from an executing SACLIB program. This program instrumentation is transparent both to SACLIB maintainers and clients. This mechanism allows the automated creation of regression test suites during the execution of normal SACLIB programs. Using code generation and auto-tuning, we allow high performance implementations of the Taylor shift, de Casteljau's algorithm, and the Descartes Method for polynomial root isolation to be automatically tuned for different architectures. This allows a speedup of 10-20 over existing methods to be obtained on modern CPU architectures. The key to this speedup is the creation of a tiling scheme that allows the irregular structure of the computation to be tiled using a small number of tiles that are easy for a code generator to produce code for. The implementation of the Recursively Fixed Iterator and the Structure Protecting Iterator provide memory safety by using C++ template metaprograms that selectively disable certain classes of side effects in programs using the iterators. Other safety properties can be achieved using similar disabling of side effects. We believe that the most important continuation of the work presented here is the development of programming language techniques to allow programmers to control where their code should sit along the spectrum of the absence of side effects in pure functional languages and the unrestricted side effects of imperative language.
Laparoscopic Treatment of a Rare Right Diaphragmatic Rupture with Small Bowel Herniation after Blunt Thoracic Trauma
Authors: Hoffmann H. , Oertli D. , Heizmann O.
Published: June 2010

Blunt traumatic diaphragmatic rupture (BTDR) is a life-threatening condition with an incidence from 0,8%–1,6% in blunt trauma, mostly located on the left side. The main prognostic factors are severe side injuries and the delay of diagnosis. We present a rare case of a 68-year-old female, with an isolated right diaphragm rupture. The diagnosis was done with a delay of 4 days by thoracic radiographs, which showed a herniation of small bowel into the right thoracic cavity. A reposition of the small bowel and a closure of the diaphragmatic defect by running suture were carried out laparoscopicly. Although large prospective studies concerning the outcome of laparoscopic approach to right BTDR are still missing, we could show, that laparoscopy can be performed safely in right traumatic diaphragm rupture.
Time in Care for Older People Living in Nursing Homes
Authors: Thorsell K. B. E. , Nordström B. M. , Fagerström L. , Sivberg B. V.
Published: June 2010

In order to measure actual care needs in relation to resources required to fulfill these needs, an instrument (Time in Care) with which to evaluate care needs and determine the time needed for various care activities has been developed with the aim of assessing nursing intensity in municipal care for older people. Interreliability (ICC=0.854) of time measurements (n=10'546) of 32 nursing activities in relation to evaluated care levels in two nursing homes (staffn=81) has been determined. Nursing intensity for both periods at the two nursing homes comprised on average a direct care time of 75 (45%) and 101 (42%) minutes, respectively. Work time was measured according to actual schedule (462 hours per nursing home during two weeks). Given that the need for care was high, one must further investigate if the quality of care the recipients received was sufficiently addressed.
Chemical Contamination Sensor for Phosphate Ester Hydraulic Fluids
Authors: Paul Sumit , Legner Wolfgang , Krenkow Angelika , Müller Gerhard , Lemettais Thierry , Pradat Francois , Hertens Delphine
Published: June 2010

The paper deals with chemical contamination monitoring in phosphate-ester-based hydraulic fluids using nondispersive infrared (NDIR) optical absorption. Our results show that NDIR monitoring allows detecting the take-up of water into such fluids and their hydrolytic disintegration as these become additionally stressed by Joule heating. Observations on the O–H stretching vibration band (3200–3800 ) are used for determining the free water content (0–1.5%) and the Total Acid Number (0–1 mgKOH/g). Both quantities can be assessed by monitoring the strength and the asymmetry of the O–H vibration band with regard to the free water absorption band centred around 3500 . As such optical parameters can be assessed without taking fluid samples from a pressurised hydraulic system, fluid degradation trends can be established based on regular measurements, before irreversible damage to the fluid has occurred. Therefore maintenance actions can be planned accordingly, which is very important for the airline, as unscheduled maintenance disturbs the flights organisation and often generates money loss.