bluuebunny/crossref_metadata_2025 huggingface dataset:
The challenge of obtaining therapeutic levels of genetically modified hematopoietic stem cells in β‐thalassemia patients
Authors: Persons Derek A.
Published: August 2010

Hematopoietic stem cells (HSCs) function to provide the individual with a continuing supply of blood cells over many decades. To this end, HSCs have evolved unique mechanisms for self‐preservation, including resistance to viral infection. Unfortunately, this characteristic may impede the ability to achieve high levels of gene transfer mediated by HIV‐based lentiviral vectors. This is an important consideration for gene therapy efforts being undertaken for β‐thalassemia. In particular, the study of β‐thalassemia patients that underwent allogeneic stem cell transplantation and developed stable, long‐term mixed chimerism suggests that HSC gene transfer levels of greater than 25% will be needed for a robust therapeutic effect in such patients. Available pre‐clinical and clinical trial lentiviral gene transfer studies suggest that improvements are needed to achieve this goal. Here, we review what level of gene transfer is needed in the context of varying degrees of β‐globin deficiency, what level is currently achievable, and the areas of research which may be fruitful in improving the likelihood of success for patients with the severest forms of β‐thalassemia.
Therapy for β‐globinopathies: a brief review and determinants for successful and safe correction
Authors: Perumbeti Ajay , Malik Punam
Published: August 2010

Gene therapy for β‐globinopathies, particularly β‐thalassemia and sickle cell anemia, hold much promise for the future, as a one time cure for these common and debilitating disorders. Correction of the β‐globinopathies using lentivirus vectors (LV) carrying the β‐ or γ‐globin genes and elements of the locus control region has been well established in murine models, and a good idea of “what it will take to cure these diseases” has been developed in the first decade of the twenty‐first century. A clinical trial using one such vector has been initiated in France while other trials are in development. Vector improvements to enhance the safety and efficiency of LV are being explored, while newer strategies, like homologous recombination in induced pluripotent cells for correction of sickle cell anemia, has been shown as a proof‐of‐concept. Here we provide a review of current progress in genetic correction of β‐globin disorders.
Magnetic resonance assessment of iron overload by separate measurement of tissue ferritin and hemosiderin iron
Authors: Wu Ed X. , Kim Daniel , Tosti Christina L. , Tang Haiying , Jensen Jens H. , Cheung Jerry S. , Feng Li , Au Wing‐Yan , Ha Shau‐Yin , Sheth Sujit S. , Brown Truman R. , Brittenham Gary M.
Published: August 2010

With transfusional iron overload, almost all the excess iron is sequestered intracellularly as rapidly mobilizable, dispersed, soluble ferritin iron, and as aggregated, insoluble hemosiderin iron for long‐term storage. Established magnetic resonance imaging (MRI) indicators of tissue iron (R2, R2*) are principally influenced by hemosiderin iron and change slowly, even with intensive iron chelation. Intracellular ferritin iron is evidently in equilibrium with the low‐molecular‐weight cytosolic iron pool that can change rapidly with iron chelation. We have developed a new MRI method to separately measure ferritin and hemosiderin iron, based on the non‐monoexponential signal decay induced by aggregated iron in multiple‐spin‐echo sequences. We have initially validated the method in agarose phantoms and in human liver explants and shown the feasibility of its application in patients with thalassemia major. Measurement of tissue ferritin iron is a promising new means to rapidly evaluate the effectiveness of iron‐chelating regimens.
Critical appraisal of growth retardation and pubertal disturbances in thalassemia
Authors: Chatterjee Ratna , Bajoria Rekha
Published: August 2010

Growth and pubertal disturbances are the commonest endocrinopathies in homozygous thalassemia, accounting for significant morbidity in 70–80% children and adolescents globally. This review focuses on the pathophysiology of the endocrinopathy from a historical perspective and altered natural history induced by better care due to transfusion and chelation therapy. We have also discussed clinical features, diagnosis, and management strategies of growth retardation, sexual infantilism, pubertal aberrations, and scope of growth hormone, sex steroids, and other endocrine therapies. The article also emphasizes current and future strategies for screening, monitoring of growth and pubertal disturbances, and early intervention for the restoration of fertility potential and bone mass in the affected individuals.
Combined iron chelation therapy
Authors: Galanello Renzo , Agus Annalisa , Campus Simona , Danjou Fabrice , Giardina Patricia J. , Grady Robert W.
Published: August 2010

Patients with thalassemia major accumulate body iron over time as a consequence of continuous red blood cell transfusions which cause hepatic, endocrine, and cardiac complications. Despite the availability of three iron chelators, some patients fail to respond adequately to monotherapy with any of them. Combination therapy, consisting in the use of two chelators on the same day, has been introduced to increase the efficacy and to induce negative iron balance in patients with severe iron overload. Extensive long‐term experience has shown that combined chelation with deferiprone and deferoxamine (DFO) rapidly reduces liver iron, serum ferritin, and myocardial siderosis, improves cardiac function, reverses and prevents endocrine complications, reduces cardiac mortality, and improves survival. Side effects, though significant, are manageable if properly monitored. Preliminary promising results have been obtained using combined chelation with deferasirox and DFO. As more drug combination regimes are evaluated, it should be possible to better tailor iron chelation to the needs of the patients, minimizing toxicity and maximizing efficacy throughout life.
Fetal globin gene inducers: novel agents and new potential
Authors: Perrine Susan P. , Castaneda Serguei A. , Chui David H.K. , Faller Douglas V. , Berenson Ronald J. , Siritanaratku Noppadol , Fucharoen Suthat
Published: August 2010

Inducing expression of endogenous fetal globin (γ‐globin) gene expression to 60–70% of alpha globin synthesis produces β‐thalassemia trait globin synthetic ratios and can reduce anemia to a mild level. Several classes of therapeutics have induced γ‐globin expression in beta‐thalassemia patients and subsequently raised total hemoglobin levels, demonstrating proof‐of‐concept of the approach. Butyrate treatment eliminated transfusion requirements in formerly transfusion‐dependent patients with treatment for as long as seven years. However, prior generation inducers were not readily applicable for widespread use. Currently, a novel oral dual‐action therapeutic, sodium 2,2‐dimethylbutyrate, is in clinical trials, an oral decitabine formulation is under development, and agents with complementary mechanisms of action can be applied in combined regimens. Identification of three major genetic trait loci which modulate clinical severity provides avenues for developing tailored regimens. These refinements offer renewed potential to apply fetal globin induction as a treatment approach in patient‐friendly regimens that can be used worldwide.
Hepcidin and Hfe in iron overload in β‐thalassemia
Authors: Gardenghi Sara , Ramos Pedro , Follenzi Antonia , Rao Niva , Rachmilewitz Eliezer A. , Giardina Patricia J. , Grady Robert W. , Rivella Stefano
Published: August 2010

Hepcidin (HAMP) negatively regulates iron absorption, degrading the iron exporter ferroportin at the level of enterocytes and macrophages. We showed that mice with β‐thalassemia intermedia (th3/+) have increased anemia and iron overload. However, their hepcidin expression is relatively low compared to their iron burden. We also showed that the iron metabolism gene Hfe is down‐regulated in concert with hepcidin in th3/+ mice. These observations suggest that low hepcidin levels are responsible for abnormal iron absorption in thalassemic mice and that down‐regulation of Hfe might be involved in the pathway that controls hepcidin synthesis in β‐thalassemia. Therefore, these studies suggest that increasing hepcidin and/or Hfe expression could be a strategy to reduces iron overload in these animals. The goal of this paper is to review recent findings that correlate hepcidin, Hfe, and iron metabolism in β‐thalassemia and to discuss potential novel therapeutic approaches based on these recent discoveries.
Health care transition in thalassemia: pediatric to adult‐oriented care
Authors: Levine Laurice , Levine Matthew
Published: August 2010

Improved technology and medical advances have increased the lifespan for people with thalassemia. As thalassemia is no longer exclusively a pediatric blood disorder, consideration must now be given to transition planning from pediatric to adult care. The complexity of thalassemia disease, coupled with the changing face of U.S. health care, creates barriers to transitional planning. Additional barriers develop because this chronic disease is less common in adults, leaving caregivers unprepared to facilitate proper adult treatment. This paper will discuss two common U.S. health care settings where care is provided to adults with thalassemia. It will also offer health care administrators, providers, policy makers, and the thalassemia community at large some recommendations on the provision of comprehensive, quality care to assure the best possible outcomes no matter what setting is available to adult patients living with thalassemia.
Early–flowering taxa of Euphrasia (Scrophulariaceae) on Gotland, Sweden
Authors: Karlsson Thomas
Published: August 2010

Two taxa of early–flowering Euphrasia occur on the island of Gotland, Sweden, viz. E. stricla J. P. Wolff ex J. F. Lehm. var. tenuis (Brenner) Jalas and E. stricta var. suecica (Murb. & Wettst. ex Wettst.) Karlsson comb. nov. They are restricted to hay–meadows and, being sensitive to grazing and competition from taller plants, are now disappearing because hay–making on seminatural grassland has lost its economic importance and is being abandoned. Field studies showed that var. tenuis is restricted to meadows of the Arrhenatheretalia type, var. suecica to aspects of Molinietalia which approach Mesobrometum. A statistical analysis of mass collections showed that the best distinguishing character between var. suecica and var. tenuis is that glandular hairs on the leaves are absent or only occasional in the former; in addition, var. suecica has smaller flowers and narrower leaves with a cuneate leaf–base. These differences remained in cultivated material. However, the leaf shape is greatly dependent on vigour and is difficult to use for diagnostic purposes. There is a great deal of variation among populations, especially within var. suecica. Investigation of herbarium material confirmed the results from the analysis of mass collections, and also suggested that introgression from var. tenuis into var. suecica has taken place. Var. tenuis has spread to Gotland, possibly as early as during the Iron Age when haymaking became important, whereas var. suecica may have originated on the island by selection from eglandular, autumnal variants of E. stricta.
Combined strategies for enhancing the transdermal absorption of midazolam through human skin
Authors: Balaguer-Fernández Cristina , Femenía-Font Andrés , Muedra Vicente , Merino Virginia , López-Castellano Alicia
Published: August 2010

Objectives

Midazolam administration by intravenous or intramuscular injection produces pain and stress. For this reason, alternative methods of administration have been proposed. The transdermal administration of midazolam could improve patient comfort, which is especially important for children in the pre-operative period. We aimed to assess the effect of iontophoresis and chemical percutaneous enhancers applied individually and together, to determine if a synergistic effect is achieved when both enhancement techniques are simultaneously employed.

Methods

This work reports the characterization of the passive diffusion of midazolam hydrochloride through human skin in vitro and evaluates the effect of iontophoresis application and chemical percutaneous enhancers on said diffusion when employed both individually and in combination.

Key findings

Percutaneous absorption assays demonstrated that the physical technique of iontophoresis, when applied alone, moderately increased midazolam hydrochloride permeation flux through human skin, producing a similar effect to that obtained with R-(+)-limonene chemical enhancer. Among the strategies assayed, it was observed that Azone produced the most pronounced enhancement effect when applied separately. The combination of pre-treatment with Azone and iontophoresis exhibited a higher capacity for enhancing the transdermal flux of midazolam through human skin than Azone alone.

Conclusions

In conclusion, when applied individually, Azone exhibited the greatest enhancement effect on the transdermal diffusion of midazolam of the various strategies assayed. The combination of Azone and iontophoresis produce the highest transdermal steady-state flux of midazolam but no synergic effect was achieved when the two enhancement strategies were applied in combination, showing that although selecting the best conditions for iontophoresis application, it is less effective for augmenting the transdermal delivery of midazolam than the chemical enhancer Azone.
Difference in blood tacrolimus concentration between ACMIA and MEIA in samples with low haematocrit values
Authors: Doki Kosuke , Homma Masato , Hori Tetsuo , Tomita Takashi , Hasegawa Yuichi , Ito Satoshi , Fukunaga Kiyoshi , Kaneko Michio , Chiba Shigeru , Sumida Takayuki , Ohkohchi Nobuhiro , Kohda Yukinao
Published: August 2010

Objectives

The aim was to compare blood tacrolimus concentrations in anaemic patients between affinity column-mediated immunoassay (ACMIA) and microparticle enzyme immunoassay (MEIA).

Methods

Blood concentrations of tacrolimus in 235 whole-blood samples from 64 patients treated with tacrolimus were determined by the two assay methods. Fifty-three samples had low haematocrit (Ht) values (<25%), whereas the other samples had normal Ht values.

Key findings

Measured tacrolimus concentrations in samples with normal Ht values did not differ between ACMIA and MEIA (median, range; 6.6, 0–29.1 vs 7.3, 0–27.4 ng/ml). On the other hand, MEIA determined significantly higher tacrolimus concentrations in samples with lower Ht values compared with ACMIA (14.0, 2.4–25.7 vs 11.5, 0–21.3 ng/ml; P < 0.05). This difference was caused by overestimated blood concentrations in MEIA derived from lower Ht values, which could be corrected using the Ht value for each sample (calculated MEIA (MEIAcalc)). The corrected concentrations (MEIAcalc; 10.8, 0–21.3 ng/ml) were comparable with those of ACMIA. It was confirmed that the difference in concentrations between ACMIA and MEIA was remarkable in routine monitoring of blood tacrolimus for a liver transplant recipient with anaemia.

Conclusions

ACMIA can be applied to routine therapeutic drug monitoring of tacrolimus therapy in anaemic patients.
Development and oral bioavailability assessment of a supersaturated self-microemulsifying drug delivery system (SMEDDS) of albendazole
Authors: Mukherjee Tusharmouli , Plakogiannis Fotios M
Published: August 2010

Objectives

Albendazole's (ABZ) poor aqueous solubility is a major determinant of its variable therapeutic response (20–50%). The purpose of this study was to develop and optimize the composition of a self-microemulsifying drug delivery system (SMEDDS) of ABZ and assess its oral pharmacokinetics in rabbits.

Methods

A D-optimal mixture design of experiments was used to select the levels of constraints of the formulation variables. The predicted composition was optimized using four responses: dispersion performance, droplet sizes, dissolution efficiency (DE) and time for 85% drug release (t85%).

Key findings

The optimal composition of the ABZ-SMEDDS formulation, with approximately 5 mg/g drug loading of ABZ, was predicted to be Cremophor EL (30% w/w), Tween 80 (15% w/w), Capmul PG-8 (10% w/w) and acidified PEG 400 (45% w/w). An increase of 63% in the relative bioavailability compared with the commercial suspension was obtained with ABZ-SMEDDS as measured by albendazole sulfoxide (ABZSO) plasma levels. The area under the curve (AUC0→24h) and the peak plasma concentration (Cmax) of ABZ-SMEDDS was higher than those obtained with the commercial suspension by 56% and 52%, respectively.

Conclusions

This study demonstrates a strategy for the development of a supersaturated SMEDDS formulation of a drug with low aqueous solubility.
FEYNMAN PERTURBATION THEORY FOR GAUGE THEORY ON TRANSVERSE LATTICE
Authors: KARNEVSKIY M. S. , PASTON S. A.
Published: August 2010

Feynman perturbation theory for non-Abelian gauge theory in light-like gauge is investigated. A lattice along two spacelike directions is used as a gauge invariant ultraviolet regularization. For preservation of the polynomiality of action, we use as independent variables arbitrary (nonunitary) matrices related to the link of the lattice. The action of the theory is selected in such a way to preserve as much as possible the rotational invariance, which remains after an introduction of the lattice, as well as to make superfluous degrees of freedom vanish in the limit of removing the regularization. Feynman perturbation theory is constructed and diagrams which does not contain ultraviolet divergences are analyzed. The scheme of renormalization of this theory is discussed.
HOW CAN CP VIOLATION IN THE NEUTRINO SECTOR BE LARGE IN A 2 ↔ 3 SYMMETRIC MODEL?
Authors: KOIDE YOSHIO , NISHIURA HIROYUKI
Published: August 2010

Based on a neutrino mass matrix model in which a 2 ↔ 3 symmetry is only broken by a phase parameter, it is investigated how the lepton mixing matrix can deviate from the so-called tribimaximal mixing under a condition that CP is maximally violated.
ELECTROMAGNETIC EXCITATIONS OF An QUANTUM HALL DROPLETS
Authors: DAOUD MOHAMMED , JELLAL AHMED , GUEJDI ABDELLAH OUELD
Published: August 2010

The classical description of An internal degrees of freedom is given by making use of the Fock–Bargmann analytical realization. The symplectic deformation of phase space, including the internal degrees of freedom, is discussed. We show that the Moser's lemma provides a mapping to eliminate the fluctuations of the symplectic structure, which become encoded in the Hamiltonian of the system. We discuss the relation between Moser and Seiberg–Witten maps. One physics application of this result is the electromagnetic excitation of a large collection of particles, obeying the generalized An statistics, living in the complex projective space CPk with U(1) background magnetic field. We explicitly calculate the bulk and edge actions. Some particular symplectic deformations are also considered.
STANDARD MODEL IN AdS SLICE WITH UV-LOCALIZED HIGGS FIELD
Authors: MIRONOV SERGEY , OSIPOV MIKHAIL , RAMAZANOV SABIR
Published: August 2010

We discuss five-dimensional Standard Model in a slice of AdS space–time with the Higgs field residing near or on the UV brane. Allowing fermion fields to propagate in the bulk, we obtain the hierarchy of their masses and quark mixings without introducing large or small Yukawa couplings. However, the interaction of fermions with the Higgs and gauge boson KK excitations gives rise to FCNC with no built-in suppression mechanism. This strongly constrains the scale of KK masses. We also discuss neutrino mass generation via KK excitations of the Higgs field. We find that this mechanism is subdominant in the scenarios of spontaneous symmetry breaking we consider.
ANISOTROPIC BIANCHI-V PERFECT FLUID SPACE–TIME WITH VARIABLES G AND Λ
Authors: SINGH C. P. , BEESHAM A.
Published: August 2010

We study spatially homogeneous and anisotropic Bianchi-V perfect fluid cosmological model with variable G and Λ. Exact solutions to the field equations in the case of particle creation and in the absence of particle creation are obtained by assuming a constant deceleration parameter. The model has a big-bang-type singularity at the initial time t = 0. We find that a constant value of deceleration parameter is reasonable for a description of the present day universe. We also observe that the variable G does not necessarily imply particle creation. The behavior of observationally important parameters such as the expansion scalar, mean anisotropic parameter and shear scalar are discussed. It is observed that the solutions are compatible with the results of recent observations.
INTERPRETING THE BOUNDS ON SOLAR DARK MATTER INDUCED MUONS AT SUPER-KAMIOKANDE IN THE LIGHT OF CDMS RESULTS
Authors: BANDYOPADHYAY ABHIJIT , CHAKRABORTY SOVAN , MAJUMDAR DEBASISH
Published: August 2010

We consider the recent limits on dark matter–nucleon elastic scattering cross-section from the analysis of CDMS II collaboration using the two signal events observed in CDMS experiment. With these limits we try to interpret the super-Kamiokande (SK) bounds on the detection rates of up-going muons induced by the neutrinos that are produced in the sun from the decay of annihilation products of dark matter (WIMP's) captured in the solar core. Calculated rates of up-going muons for different annihilation channels at SK using CDMS bounds are found to be orders below the predicted upper limits of such up-going muon rates at SK. Thus there exists room for enhancement (boost) of the calculated rates using CDMS limits for interpreting SK bounds. Such a feature is expected to represent the PAMELA data with the current CDMS limits. We also show the dependence of such a possible enhancement factor (boost) on WIMP mass for different WIMP annihilation channels.
A framework to enforce access control over data streams
Authors: Carminati Barbara , Ferrari Elena , Cao Jianneng , Tan Kian Lee
Published: August 2010

Although access control is currently a key component of any computational system, it is only recently that mechanisms to guard against unauthorized access to streaming data have started to be investigated. To cope with this lack, in this article, we propose a general framework to protect streaming data, which is, as much as possible, independent from the target stream engine. Differently from RDBMSs, up to now a standard query language for data streams has not yet emerged and this makes the development of a general solution to access control enforcement more difficult. The framework we propose in this article is based on an expressive role-based access control model proposed by us. It exploits a query rewriting mechanism, which rewrites user queries in such a way that they do not return tuples/attributes that should not be accessed according to the specified access control policies. Furthermore, the framework contains a deployment module able to translate the rewritten query in such a way that it can be executed by different stream engines, therefore, overcoming the lack of standardization. In the article, besides presenting all the components of our framework, we prove the correctness and completeness of the query rewriting algorithm, and we present some experiments that show the feasibility of the developed techniques.
Efficient and accurate nearest neighbor and closest pair search in high-dimensional space
Authors: Tao Yufei , Yi Ke , Sheng Cheng , Kalnis Panos
Published: August 2010

Nearest Neighbor (NN) search in high-dimensional space is an important problem in many applications. From the database perspective, a good solution needs to have two properties: (i) it can be easily incorporated in a relational database, and (ii) its query cost should increase
sublinearly
with the dataset size, regardless of the data and query distributions.
Locality-Sensitive Hashing
(LSH) is a well-known methodology fulfilling both requirements, but its current implementations either incur expensive space and query cost, or abandon its theoretical guarantee on the quality of query results.

Motivated by this, we improve LSH by proposing an access method called the
Locality-Sensitive B-tree
(LSB-tree) to enable fast, accurate, high-dimensional NN search in relational databases. The combination of several LSB-trees forms a
LSB-forest
that has strong quality guarantees, but improves dramatically the efficiency of the previous LSH implementation having the same guarantees. In practice, the LSB-tree itself is also an effective index which consumes linear space, supports efficient updates, and provides accurate query results. In our experiments, the LSB-tree was faster than: (i) iDistance (a famous technique for exact NN search) by two orders of magnitude, and (ii) MedRank (a recent approximate method with nontrivial quality guarantees) by one order of magnitude, and meanwhile returned much better results.

As a second step, we extend our LSB technique to solve another classic problem, called Closest Pair (CP) search, in high-dimensional space. The long-term challenge for this problem has been to achieve
subquadratic
running time at very high dimensionalities, which fails most of the existing solutions. We show that, using a LSB-forest, CP search can be accomplished in (worst-case) time significantly lower than the quadratic complexity, yet still ensuring very good quality. In practice, accurate answers can be found using just two LSB-trees, thus giving a substantial reduction in the space and running time. In our experiments, our technique was faster: (i) than distance browsing (a well-known method for solving the problem exactly) by several orders of magnitude, and (ii) than D-shift (an approximate approach with theoretical guarantees in low-dimensional space) by one order of magnitude, and at the same time, outputs better results.
Views and queries
Authors: Nash Alan , Segoufin Luc , Vianu Victor
Published: August 2010

We investigate the question of whether a query
Q
can be answered using a set
V
of views. We first define the problem in information-theoretic terms: we say that
V
determines
Q
if
V
provides enough information to uniquely determine the answer to
Q
. Next, we look at the problem of rewriting
Q
in terms of
V
using a specific language. Given a view language
V
and query language
Q
, we say that a rewriting language
R
is complete for
V
-to-
Q
rewritings if every
Q
∈
Q
can be rewritten in terms of
V
∈
V
using a query in
R
, whenever
V
determines
Q
. While query rewriting using views has been extensively investigated for some specific languages, the connection to the information-theoretic notion of determinacy, and the question of completeness of a rewriting language have received little attention. In this article we investigate systematically the notion of determinacy and its connection to rewriting. The results concern decidability of determinacy for various view and query languages, as well as the power required of complete rewriting languages. We consider languages ranging from first-order to conjunctive queries.
Towards a logical reconstruction of a theory for locally closed databases
Authors: Denecker Marc , Cortés-Calabuig Álvaro , Bruynooghes Maurice , Arieli Ofer
Published: August 2010

The
Closed World Assumption
(CWA) on databases expresses the assumption that an atom not in the database is false. This assumption is applicable only in cases where the database has complete knowledge about the domain of discourse. In this article, we investigate
locally closed
databases, that is: databases that are sound but partially incomplete about their domain. Such databases consist of a standard database instance, augmented with a collection of
Local Closed World Assumptions
(LCWAs). A LCWA is a “local” form of the CWA, expressing that a database relation is complete in a certain area, called a
window of expertise
. In this work, we study locally closed databases both from a knowledge representation and from a computational perspective. At the representation level, the approach taken in this article distinguishes between the data that is conveyed by a database and the metaknowledge about the area in which the data is complete. We study the semantics of the LCWA's and relate it to several knowledge representation formalisms. At the reasoning level, we study the complexity of, and algorithms for two basic reasoning tasks: computing
certain
and
possible
answers to queries and determining whether a database has complete knowledge on a query. As the complexity of these tasks is unacceptably high, we develop efficient
approximate
methods for query answering. We also prove that for useful classes of queries and locally closed databases, these methods are
optimal
, and thus they solve the original query in a tractable way. As a result, we obtain classes of queries and locally closed databases for which query answering is tractable.
LU factoring of non-invertible matrices
Authors: Jeffrey D. J.
Published: August 2010

The definition of the LU factoring of a matrix usually requires that the matrix be invertible. Current software systems have extended the definition to non-square and rank-deficient matrices, but each has chosen a different extension. Two new extensions, both of which could serve as useful standards, are proposed here: the first combines LU factoring with full-rank factoring, and the second extension combines full-rank factoring with fraction-free methods. Amongst other applications, the extension to full-rank, fraction-free factoring is the basis for a fractionfree computation of the Moore-Penrose inverse.
Abstract only
Authors: Radu Silviu
Published: August 2010

In this thesis we study Ramanujan's congruences and related problems from an algorithmic point of view. We present an algorithm that proves such congruences. Furthermore, we also describe an algorithm that proves identities involving certain infinite products which are tightly connected to Ramanujan's congruences. The techniques involved are based on modular forms and we spend some time on nailing down the definitions and results involved in this area. In the last part of the thesis we give a proof of a result conjectured by James Sellers about generalized Frobenius partitions, which resulted from joint work with Peter Paule.
Abstract only
Authors: Leykin Anton
Published: August 2010

Polynomial homotopy continuation is at the heart of numerical algebraic geometry, an area whose primary goal is to solve systems of polynomial equations. Recently this field developed rapidly producing several software packages that solve some problems out of reach for purely symbolic techniques. However, the homotopy tracking procedures employ heuristics to follow the homotopy continuation paths. Jointly with Carlos Beltran we have devised a certified homotopy tracking algorithm, which was implemented in Macaulay2. In addition we conducted experiments shedding light on some developments in complexity analysis of polynomial systems solving.
Abstract only
Authors: van Hoeij Mark
Published: August 2010

In 2001 a new algorithm was introduced for factoring polynomials over the rationals. The algorithm was soon adopted by several computer algebra systems because of its good practical performance. A complexity result for a slower version of the algorithm was given in a preprint [BHKS, 2004], but there remained a very large gap between the proven bound and the behavior of the implementations as observed in actual examples. This gap was closed in joint work with Andy Novocin. We give a modification of the algorithm that allows us to prove the best complexity bound for factoring in Q[x]. Moreover, unlike [BHKS, 2004], an implementation by Novocin demonstrates that this modification does not slow down the algorithm in practice.
Abstract only
Authors: Meng Lingchuan , Johnson Jeremy , Franchetti Franz , Voronenko Yevgen , Maza Marc Moreno , Xie Yuzhen
Published: August 2010

In this poster we present the use of the SPIRAL system (www.spiral.net) to generate code for modular Fast Fourier Transforms (FFTs). SPIRAL is a library generation system that automatically generates platform-tuned implementations of digital signal processing algorithms with an emphasis on fast transforms. Currently, SPRIAL can generate highly optimized fixed point and floating-point FFTs for a variety of platforms including vectorization, multi-threaded and distributed memory parallelization. The code produced is competitive with the best available code for these platforms and SPIRAL is used by Intel for its IPP (Intel Performance Primitives) and MKL (Math kernel Library) libraries.

The SPIRAL system uses a mathematical framework for representing and deriving algorithms. Algorithms are derived using rewrite rules and additional rules are used to symbolically manipulate algorithms into forms that take advantage of the underlying hardware. A search engine with a feedback loop is used to tune implementations to particular platforms. New transforms are added by introducing new symbols and their definition and new algorithms can be generated by adding new rules.

We extended SPIRAL to generate algorithms for FFT computation over finite fields. This addition required adding a new data type, several new rules and a new transform (ModDFT) definition. In addition, the unparser (where code is generated) was extended so that it can generate scalar and vectorized code for modular arithmetic. With these enhancements, the SPRIAL machinery can be applied to modular transforms that are of interest to the computer algebra community. This provides a framework for systematically optimizing these transforms, utilizing vector and parallel computation, and for automatically tuning them to different platforms. In this poster we present preliminary results from this exploration. We show that the code generated by SPIRAL, with improved cache locality and vectorization, is approximately ten times faster than the modular FFT code in the modpn library.
Abstract only
Authors: Youse Bryan , Saunders B. David
Published: August 2010

Bitslicing is a data compression technique useful for fast exact linear algebra over finite fields whose elements are significantly smaller than a single machine word. It involves striping the number of bits used to represent field elements over the same number of machine words. Thus, this data layout is maximally storage-efficient. We showcase the computational advantages. We also discuss practical challenges which arise when employing this scheme on large matrices and their sub-matrices over GF(3) with algorithms written to work generically with matrices over GF(q), for any q.
Abstract only
Authors: Fang Tingting , van Hoeij Mark
Published: August 2010

For second order linear ordinary differential equations with coefficients in C(x), we present an algorithm to reduce, whenever possible, the equation to an equation defined over a subfield of C(x). At the moment, we have implemented 2-descent, which means that if there exists a reduction to a subfield of index 2, then we can find it. If n is the number of true singularities, then 2-descent, if it exists, reduces the number of true singularities to at most n/2 + 2. In 12 out of the 17 examples sent to us by Bostan and Kauers, we found that repeated use of 2-descent reduced their regular singular equation down to 3 singularities, which means that 2-descent allows us to find 2F1-hypergeometric type solutions for about two third's of their equations.
CTP-based programming languages?
Authors: Haftmann Florian , Kaliszyk Cezary , Neuper Walther
Published: August 2010

This paper discusses plans for joint work in order to gain early feedback from the community. Three lines of work pursued independently so far shall be joined: (1) narrowing the gap between declarative program specification and program generation already working in Isabelle, (2) reusing work, which embedded an input-response-loop resembling Computer Algebra Systems (CAS) into HOL Light, and (3) reconstructing an experimental language for applied mathematics by exploiting established as well as emerging features of Isabelle/Isar.

These plans have to be seen as part of a variety of highly active research areas -- on "integration of the deduction and the computational power" of Computer Theorem Proving (CTP) and CAS respectively (Calculemus), on "innovative theoretical and technological solutions for content-based systems" (MKM), on "Programming Languages for Mechanized Mathematics Systems" (PLMMS), just to cite from some related interest groups. Facing the abundant variety of approaches, of intermediate results and of ongoing developments, and taking under consideration the many difficulties in integrating such approaches, we pursue pragmatic goals: Design a component indispensable for working engineers, a programming language for engineering applications. Use Isabelle for an experimental embedding of the language, which is useful at least in engineering education as soon as possible.
LEMA
Authors: Lefèvre Vincent , Théveny Philippe , de Dinechin Florent , Jeannerod Claude-Pierre , Mouilleron Christophe , Pfannholzer David , Revol Nathalie
Published: August 2010

Generating certified and efficient numerical codes requires information ranging from the mathematical level to the representation of numbers. Even though the mathematical semantics can be expressed using the content part of MathML, this language does not encompass the implementation on computers. Indeed various arithmetics may be involved, like floating-point or fixed-point, in fixed precision or arbitrary precision, and current tools do not handle all of these.

Therefore we propose in this paper LEMA (Langage pour les Expressions Math'ematiques Annot'ees), a descriptive language based on MathML with additional expressiveness. LEMA will be used during the automatic generation of certified numerical codes. Such a generation process typically involves several steps, and LEMA would thus act as a glue to represent and store the information at every stage.

First, we specify in the language the characteristics of the arithmetic as described in the IEEE 754 floatingpoint standard: formats, exceptions, rounding modes. This can be generalized to other arithmetics. Then, we use annotations to attach a specific arithmetic context to an expression tree. Finally, considering the evaluation of the expression in this context allows us to deduce several properties on the result, like being exact or being an exception. Other useful properties include numerical ranges and error bounds.
Aggressive Treatment Approach for Cloacogenic Carcinoma of the Anorectum: Report from a Single Cancer Center
Authors: Bertani Emilio , Chiappa Antonio , Mazzarol Giovanni , Contino Gianmarco , Lazzari Roberta , Zampino Maria Giulia , Viale Giuseppe , Andreoni Bruno
Published: August 2010

Background/Aims: The prognosis of cloacogenic carcinoma of the anorectum has rarely been investigated, and its clinical behavior is supposed to be similar to common squamous anal cancers. During the last 10 years, chemoradiation treatment (CRT) has been considered the standard of care for anal cancer. Methods: We retrospectively investigated the treatment of cloacogenic cancers treated within the framework of a multidisciplinary cancer center team during an 8-year period. The medical records of 7 patients affected by cloacogenic carcinoma were analyzed. Three patients presented distant metastases at the time of diagnosis. CRT using 5-fluorouracil + mitomycin or cisplatin was considered the gold standard for those cases amenable to cure. Results: After a mean follow-up time of 33 months (range 9–100), disease recurrence or progression was observed in 6 patients, which caused death in 3 of them. Three- and 5-year actuarial overall survival rates were 71 and 48%, respectively. Conclusions: Our data seem to suggest that the cloacogenic origin could present prognostic relevance within the wide spectrum of anal cancers. This should be carefully considered when submitting patients to aggressive and prolonged treatments. However, this hypothesis needs to be confirmed by larger series of this disease.
Multi-Modal Hallucinations and Cognitive Function in Parkinson’s Disease
Authors: Katzen Heather , Myerson Connie , Papapetropoulos Spiridon , Nahab Fatta , Gallo Bruno , Levin Bonnie
Published: August 2010

Background/Aims: Hallucinations have been linked to a constellation of cognitive deficits in Parkinson’s disease (PD), but it is not known whether multi-modal hallucinations are associated with greater neuropsychological dysfunction. Methods: 152 idiopathic PD patients were categorized based on the presence or absence of hallucinations and then were further subdivided into visual-only (VHonly; n = 35) or multi-modal (VHplus; n = 12) hallucination groups. All participants underwent detailed neuropsychological assessment. Results: Participants with hallucinations performed more poorly on select neuropsychological measures and exhibited more mood symptoms. There were no differences between VHonly and VHplus groups. Conclusions: PD patients with multi-modal hallucinations are not at greater risk for neuropsychological impairment than those with single-modal hallucinations.
Low Cancer Rates among Patients with Dementia in a Population-Based Register Study in Sweden
Authors: Attner Bo , Lithman Thor , Noreen Dennis , Olsson Håkan
Published: August 2010

Background: Some studies have suggested a lower incidence of cancer in patients with dementia. We studied this further for 18 cancer types in population-based registers. Methods: In 19,756 cases and in 147,324 age- and sex-matched controls a diagnosis of dementia was studied 9–45 months prior to the diagnosis of cancer. Results: Overall a diagnosis of dementia was significantly less common among the cancer cases (risk ratio, RR = 0.60; 95% CI = 0.52–0.69). Conclusion: The study confirms previous findings that patients with dementia have a lower risk of cancer. Because the effect was seen for all tumour types and especially for patients older than 70 years and since the deficit was more pronounced for patients with tumours situated within the body, the data suggest that malignancies are underdiagnosed for persons with dementia.
Androgen Replacement Therapy in Late-Onset Hypogonadism: Current Concepts and Controversies – A Mini-Review
Authors: Mäkinen Juuso I. , Huhtaniemi Ilpo
Published: August 2010

Background: Normal testicular function is essential for the maintenance of male physical strength and behaviour irrespective of age. A new term of late-onset hypogonadism (LOH) has been coined for the condition of decreased testosterone (T) and hypogonadal symptoms in ageing men. Objective: The most important testicular hormone, T, is responsible for the gender-specific androgenic-anabolic effects in men. Testicular T production remains stable until around the age of 40 years after which it declines by 1–2% annually. Despite this age-related decline, serum T levels in most older men remain within the reference range of younger men. The decreasing androgen levels are paralleled by well-defined objective biological and nonspecific subjective signs and symptoms of ageing. Because these symptoms are similar to those observed in young men with documented hypogonadism, androgen replacement therapy (ART) has been considered a logical way to treat them. Methods: A thorough review of the existing literature was performed to evaluate the current concepts and controversies related to ageing men and ART. Results: Although it is intuitively logical that the symptoms of LOH are due to the ageing-related deficiency of T, and that they can be reversed by ART, the evidence for this is still variable and often weak. In particular, evidence-based information about long-term benefits and risks of ART in ageing men is largely missing. Conclusions: Despite widespread use, evidence-based proof for the objective benefits and side effects of ART of elderly men is still scanty, and such treatments should be considered experimental.
Tamed Transparency: How Information Disclosure under the Global Reporting Initiative Fails to Empower
Authors: Dingwerth Klaus , Eichinger Margot
Published: August 2010

In this contribution, we explore the tensions that seem inherent in the claim that transparency policies “empower” the users of disclosed information vis-àvis those who are asked to provide the information. Since these tensions are particularly relevant in relation to voluntary disclosure, our analysis focuses on the Global Reporting Initiative (GRI) as the world's leading voluntary corporate non-financial reporting scheme. Corporate sustainability reporting is often hailed as a powerful instrument to improve the environmental performance of business and to empower societal groups, including consumers, in their relations with the corporate world. Yet, our analysis illustrates that the relationship between transparency and empowerment is conflictual at all four levels of activity examined in this article: in the rhetoric and policies of the GRI as well as in the actual reporting practice and in the activities of intermediaries in response to the organization's disclosure standard.
The National Context for Transparency-based Global Environmental Governance
Authors: Florini Ann
Published: August 2010

Transparency-based global environmental governance, like all global governance, necessarily plays out in national contexts. Its efficacy is shaped not only by global politics but also by the norms and capacities prevailing within countries. Over the past two decades, there has been an extraordinary upheaval in transparency views and practices in numerous countries, rich and poor, democratic and authoritarian. This multi-faceted development has been driven by such varied factors as democratization, privatization, and changing views about appropriate regulatory practices. These changes provide the crucial context for understanding the transparency transformation that is currently unfolding within global environmental governance, as well as what its promise, limitations and implications in practice might be in diverse national contexts.
The Future of Transparency: Power, Pitfalls and Promises
Authors: Mol Arthur P. J.
Published: August 2010

The growing attention to transparency is not an accidental and fashionable wave, soon to be replaced by another timely topic in environmental governance. Transparency is here to stay and to further develop in environmental politics, as it piggy-backs on a number of wider social developments. In assessing the achievements of transparency to date, this article concludes that it has on balance been positive for democracy. But this overall positive past assessment does not automatically extend into the future, as new challenges (and thus new research agendas) lie ahead. The growing importance attached to transparency in environmental politics ensures that it becomes a central object of power struggles, with uncertain outcomes in terms of democracy as well as environmental effects. Markets and states seek to capture transparency arrangements for their own goals, which may not necessarily be in line with assumed normative linkages between transparency, democracy and participation.