bluuebunny/crossref_metadata_2025 huggingface dataset:
Changes in bacterial community structure associated with coastal copper enrichment
Authors: Morán Ana C , Hengst Martha B , de la Iglesia Rodrigo , Andrade Santiago , Correa Juan A , González Bernardo
Published: June 2008

Marine bacterial communities isolated from the water column, sediment, the rock surface, and the green seaweed Ulva compressa were studied in an intertidal ecosystem. The study area included a coastal zone chronically affected by copper mine waste disposals. Bacterial community composition was analyzed by terminal restriction fragment length polymorphism (T-RFLP) of 16S rRNA genes, and multivariate analyses of T-RFLP data sets were used for comparisons. Results showed that diversity and richness indexes were not able to detect differences among compartments. However, comparisons within the same compartment clearly showed that copper enrichment was associated with changes in the composition of the bacterial communities and revealed that the magnitude of the effect depends on the compartment being considered. In this context, communities from sediments appeared as the most affected by copper enrichment. The present study also demonstrated that intertidal bacterial communities were dominated by Gammaproteobacteria, Firmicutes, and Actinobacteria and the changes in these communities were mainly due to changes in their relative abundances.
Cores of Countably Categorical Structures
Authors: Bodirsky Manuel
Published: June 2008

A relational structure is a core, if all its endomorphisms are embeddings.
This notion is important for computational complexity classification of
constraint satisfaction problems. It is a fundamental fact that every finite
structure has a core, i.e., has an endomorphism such that the structure induced
by its image is a core; moreover, the core is unique up to isomorphism. Weprove
that every \omega -categorical structure has a core. Moreover, every
\omega-categorical structure is homomorphically equivalent to a model-complete
core, which is unique up to isomorphism, and which is finite or \omega
-categorical. We discuss consequences for constraint satisfaction with \omega
-categorical templates.
Predicate Abstraction with Under-approximation Refinement
Authors: Pasareanu Corina S. , Pelanek Radek , Visser Willem
Published: June 2008

We propose an abstraction-based model checking method which relies on
refinement of an under-approximation of the feasible behaviors of the system
under analysis. The method preserves errors to safety properties, since all
analyzed behaviors are feasible by definition. The method does not require an
abstract transition relation to be generated, but instead executes the concrete
transitions while storing abstract versions of the concrete states, as
specified by a set of abstraction predicates. For each explored transition the
method checks, with the help of a theorem prover, whether there is any loss of
precision introduced by abstraction. The results of these checks are used to
decide termination or to refine the abstraction by generating new abstraction
predicates. If the (possibly infinite) concrete system under analysis has a
finite bisimulation quotient, then the method is guaranteed to eventually
explore an equivalent finite bisimilar structure. We illustrate the application
of the approach for checking concurrent programs.
Predicate Abstraction via Symbolic Decision Procedures
Authors: Lahiri Shuvendu K. , Ball Thomas , Cook Byron
Published: June 2008

We present a new approach for performing predicate abstraction based on
symbolic decision procedures. Intuitively, a symbolic decision procedure for a
theory takes a set of predicates in the theory and symbolically executes a
decision procedure on all the subsets over the set of predicates. The result of
the symbolic decision procedure is a shared expression (represented by a
directed acyclic graph) that implicitly represents the answer to a predicate
abstraction query.
We present symbolic decision procedures for the logic of Equality and
Uninterpreted Functions (EUF) and Difference logic (DIFF) and show that these
procedures run in pseudo-polynomial (rather than exponential) time. We then
provide a method to construct symbolic decision procedures for simple mixed
theories (including the two theories mentioned above) using an extension of the
Nelson-Oppen combination method. We present preliminary evaluation of our
Procedure on predicate abstraction benchmarks from device driver verification
in SLAM.
Automatic Structures: Richness and Limitations
Authors: Khoussainov Bakhadyr , Nies Andre , Rubin Sasha , Stephan Frank
Published: June 2008

We study the existence of automatic presentations for various algebraic
structures. An automatic presentation of a structure is a description of the
universe of the structure by a regular set of words, and the interpretation of
the relations by synchronised automata. Our first topic concerns characterising
classes of automatic structures. We supply a characterisation of the automatic
Boolean algebras, and it is proven that the free Abelian group of infinite
rank, as well as certain Fraisse limits, do not have automatic presentations.
In particular, the countably infinite random graph and the random partial order
do not have automatic presentations. Furthermore, no infinite integral domain
is automatic. Our second topic is the isomorphism problem. We prove that the
complexity of the isomorphism problem for the class of all automatic structures
is \Sigma_1^1-complete.
Transforming structures by set interpretations
Authors: Colcombet Thomas , Löding Christof
Published: June 2008

We consider a new kind of interpretation over relational structures: finite
sets interpretations. Those interpretations are defined by weak monadic
second-order (WMSO) formulas with free set variables. They transform a given
structure into a structure with a domain consisting of finite sets of elements
of the orignal structure. The definition of these interpretations directly
implies that they send structures with a decidable WMSO theory to structures
with a decidable first-order theory. In this paper, we investigate the
expressive power of such interpretations applied to infinite deterministic
trees. The results can be used in the study of automatic and tree-automatic
structures.
Bistable Biorders: A Sequential Domain Theory
Authors: Laird James
Published: June 2008

We give a simple order-theoretic construction of a Cartesian closed category
of sequential functions. It is based on bistable biorders, which are sets with
a partial order -- the extensional order -- and a bistable coherence, which
captures equivalence of program behaviour, up to permutation of top (error) and
bottom (divergence). We show that monotone and bistable functions (which are
required to preserve bistably bounded meets and joins) are strongly sequential,
and use this fact to prove universality results for the bistable biorder
semantics of the simply-typed lambda-calculus (with atomic constants), and an
extension with arithmetic and recursion.
We also construct a bistable model of SPCF, a higher-order functional
programming language with non-local control. We use our universality result for
the lambda-calculus to show that the semantics of SPCF is fully abstract. We
then establish a direct correspondence between bistable functions and
sequential algorithms by showing that sequential data structures give rise to
bistable biorders, and that each bistable function between such biorders is
computed by a sequential algorithm.
The Complexity of Model Checking Higher-Order Fixpoint Logic
Authors: Axelsson Roland , Lange Martin , Somla Rafal
Published: June 2008

Higher-Order Fixpoint Logic (HFL) is a hybrid of the simply typed
\lambda-calculus and the modal \lambda-calculus. This makes it a highly
expressive temporal logic that is capable of expressing various interesting
correctness properties of programs that are not expressible in the modal
\lambda-calculus.
This paper provides complexity results for its model checking problem. In
particular we consider those fragments of HFL built by using only types of
bounded order k and arity m. We establish k-fold exponential time completeness
for model checking each such fragment. For the upper bound we use fixpoint
elimination to obtain reachability games that are singly-exponential in the
size of the formula and k-fold exponential in the size of the underlying
transition system. These games can be solved in deterministic linear time. As a
simple consequence, we obtain an exponential time upper bound on the expression
complexity of each such fragment.
The lower bound is established by a reduction from the word problem for
alternating (k-1)-fold exponential space bounded Turing Machines. Since there
are fixed machines of that type whose word problems are already hard with
respect to k-fold exponential time, we obtain, as a corollary, k-fold
exponential time completeness for the data complexity of our fragments of HFL,
provided m exceeds 3. This also yields a hierarchy result in expressive power.
Algorithms for Omega-Regular Games with Imperfect Information
Authors: Chatterjee Krishnendu , Doyen Laurent , Henzinger Thomas A. , Raskin Jean-Francois
Published: June 2008

We study observation-based strategies for two-player turn-based games on
graphs with omega-regular objectives. An observation-based strategy relies on
imperfect information about the history of a play, namely, on the past sequence
of observations. Such games occur in the synthesis of a controller that does
not see the private state of the plant. Our main results are twofold. First, we
give a fixed-point algorithm for computing the set of states from which a
player can win with a deterministic observation-based strategy for any
omega-regular objective. The fixed point is computed in the lattice of
antichains of state sets. This algorithm has the advantages of being directed
by the objective and of avoiding an explicit subset construction on the game
graph. Second, we give an algorithm for computing the set of states from which
a player can win with probability 1 with a randomized observation-based
strategy for a Buechi objective. This set is of interest because in the absence
of perfect information, randomized strategies are more powerful than
deterministic ones. We show that our algorithms are optimal by proving matching
lower bounds.
Inductive Definition and Domain Theoretic Properties of Fully Abstract
Authors: Sazonov Vladimir
Published: June 2008

A construction of fully abstract typed models for PCF and PCF^+ (i.e., PCF +
"parallel conditional function"), respectively, is presented. It is based on
general notions of sequential computational strategies and wittingly consistent
non-deterministic strategies introduced by the author in the seventies.
Although these notions of strategies are old, the definition of the fully
abstract models is new, in that it is given level-by-level in the finite type
hierarchy. To prove full abstraction and non-dcpo domain theoretic properties
of these models, a theory of computational strategies is developed. This is
also an alternative and, in a sense, an analogue to the later game strategy
semantics approaches of Abramsky, Jagadeesan, and Malacaria; Hyland and Ong;
and Nickau. In both cases of PCF and PCF^+ there are definable universal
(surjective) functionals from numerical functions to any given type,
respectively, which also makes each of these models unique up to isomorphism.
Although such models are non-omega-complete and therefore not continuous in the
traditional terminology, they are also proved to be sequentially complete (a
weakened form of omega-completeness), "naturally" continuous (with respect to
existing directed "pointwise", or "natural" lubs) and also "naturally"
omega-algebraic and "naturally" bounded complete -- appropriate generalisation
of the ordinary notions of domain theory to the case of non-dcpos.
Interpolant-Based Transition Relation Approximation
Authors: Jhala Ranjit , McMillan Kenneth L.
Published: June 2008

In predicate abstraction, exact image computation is problematic, requiring
in the worst case an exponential number of calls to a decision procedure. For
this reason, software model checkers typically use a weak approximation of the
image. This can result in a failure to prove a property, even given an adequate
set of predicates. We present an interpolant-based method for strengthening the
abstract transition relation in case of such failures. This approach guarantees
convergence given an adequate set of predicates, without requiring an exact
image computation. We show empirically that the method converges more rapidly
than an earlier method based on counterexample analysis.
Decisive Markov Chains
Authors: Abdulla Parosh Aziz , Henda Noomene Ben , Mayr Richard
Published: June 2008

We consider qualitative and quantitative verification problems for
infinite-state Markov chains. We call a Markov chain decisive w.r.t. a given
set of target states F if it almost certainly eventually reaches either F or a
state from which F can no longer be reached. While all finite Markov chains are
trivially decisive (for every set F), this also holds for many classes of
infinite Markov chains. Infinite Markov chains which contain a finite attractor
are decisive w.r.t. every set F. In particular, this holds for probabilistic
lossy channel systems (PLCS). Furthermore, all globally coarse Markov chains
are decisive. This class includes probabilistic vector addition systems (PVASS)
and probabilistic noisy Turing machines (PNTM). We consider both safety and
liveness problems for decisive Markov chains, i.e., the probabilities that a
given set of states F is eventually reached or reached infinitely often,
respectively. 1. We express the qualitative problems in abstract terms for
decisive Markov chains, and show an almost complete picture of its decidability
for PLCS, PVASS and PNTM. 2. We also show that the path enumeration algorithm
of Iyer and Narasimha terminates for decisive Markov chains and can thus be
used to solve the approximate quantitative safety problem. A modified variant
of this algorithm solves the approximate quantitative liveness problem. 3.
Finally, we show that the exact probability of (repeatedly) reaching F cannot
be effectively expressed (in a uniform way) in Tarski-algebra for either PLCS,
PVASS or (P)NTM.
Call-by-value Termination in the Untyped lambda-calculus
Authors: Jones Neil D. , Bohr Nina
Published: June 2008

A fully-automated algorithm is developed able to show that evaluation of a
given untyped lambda-expression will terminate under CBV (call-by-value). The
``size-change principle'' from first-order programs is extended to arbitrary
untyped lambda-expressions in two steps. The first step suffices to show CBV
termination of a single, stand-alone lambda;-expression. The second suffices to
show CBV termination of any member of a regular set of lambda-expressions,
defined by a tree grammar. (A simple example is a minimum function, when
applied to arbitrary Church numerals.) The algorithm is sound and proven so in
this paper. The Halting Problem's undecidability implies that any sound
algorithm is necessarily incomplete: some lambda-expressions may in fact
terminate under CBV evaluation, but not be recognised as terminating.
The intensional power of the termination algorithm is reasonably high. It
certifies as terminating many interesting and useful general recursive
algorithms including programs with mutual recursion and parameter exchanges,
and Colson's ``minimum'' algorithm. Further, our type-free approach allows use
of the Y combinator, and so can identify as terminating a substantial subset of
PCF.
Lower Bounds for Complementation of omega-Automata Via the Full Automata Technique
Authors: Yan Qiqi
Published: June 2008

In this paper, we first introduce a lower bound technique for the state
complexity of transformations of automata. Namely we suggest first considering
the class of full automata in lower bound analysis, and later reducing the size
of the large alphabet via alphabet substitutions. Then we apply such technique
to the complementation of nondeterministic \omega-automata, and obtain several
lower bound results. Particularly, we prove an \omega((0.76n)^n) lower bound
for B\"uchi complementation, which also holds for almost every complementation
or determinization transformation of nondeterministic omega-automata, and prove
an optimal (\omega(nk))^n lower bound for the complementation of generalized
B\"uchi automata, which holds for Streett automata as well.
Independence and concurrent separation logic
Authors: Hayman Jonathan , Winskel Glynn
Published: June 2008

A compositional Petri net-based semantics is given to a simple language
allowing pointer manipulation and parallelism. The model is then applied to
give a notion of validity to the judgements made by concurrent separation logic
that emphasizes the process-environment duality inherent in such rely-guarantee
reasoning. Soundness of the rules of concurrent separation logic with respect
to this definition of validity is shown. The independence information retained
by the Petri net model is then exploited to characterize the independence of
parallel processes enforced by the logic. This is shown to permit a refinement
operation capable of changing the granularity of atomic actions.
Relational Parametricity and Separation Logic
Authors: Birkedal Lars , Yang Hongseok
Published: June 2008

Separation logic is a recent extension of Hoare logic for reasoning about
programs with references to shared mutable data structures. In this paper, we
provide a new interpretation of the logic for a programming language with
higher types. Our interpretation is based on Reynolds's relational
parametricity, and it provides a formal connection between separation logic and
data abstraction.
On the Expressiveness and Complexity of ATL
Authors: Laroussinie Francois , Markey Nicolas , Oreiby Ghassan
Published: June 2008

ATL is a temporal logic geared towards the specification and verification of
properties in multi-agents systems. It allows to reason on the existence of
strategies for coalitions of agents in order to enforce a given property. In
this paper, we first precisely characterize the complexity of ATL
model-checking over Alternating Transition Systems and Concurrent Game
Structures when the number of agents is not fixed. We prove that it is
\Delta^P_2 - and \Delta^P_?_3-complete, depending on the underlying multi-agent
model (ATS and CGS resp.). We also consider the same problems for some
extensions of ATL. We then consider expressiveness issues. We show how ATS and
CGS are related and provide translations between these models w.r.t.
alternating bisimulation. We also prove that the standard definition of ATL
(built on modalities "Next", "Always" and "Until") cannot express the duals of
its modalities: it is necessary to explicitely add the modality "Release".
Editorial: Biotechnology for Tissue Engineering
Authors: Taniguchi Akiyoshi
Published: June 2008

In 2008, the issue of Open Biotechnology Journal entitled “Biotechnology for Tissue Engineering” presented nine papers
focused on the biotechnology for tissue engineering.
Technologies for tissue engineering are consisted of many fields of technologies, such as cell engineering, gene technology,
nano technology and biomaterials. The purpose of this issue of Open Biotechnology Journal is to highlight studies of those
fields.
Learning with Laptops: A Multi-Method Case Study
Authors: Grimes Douglas , Warschauer Mark
Published: June 2008

This article examines the implementation of a one-to-one laptop program in three diverse schools in California. The program was carried out in one largely Hispanic low socio-economic junior high, one largely Asian Asian-American high-SES K-8 school, and in the gifted program in a medium-SES elementary school. Interviews, observations, surveys, and analysis of student work indicated that the program helped facilitate writing-intensive, information-rich, multimodal, and student-centered instruction. Analysis of test scores in English and mathematics indicate that laptop students failed to keep up with non-laptop students in the first year of implementation but made strong gains in the second year of implementation. Explanations for these outcomes are discussed.
Dream Imagery as a Result of Emotions Matching with Images
Authors: Clément Pierre
Published: June 2008

In this article I argue that the function of matching is to bind together emotions and mental images; in so doing it plays an essential role in dream imagery formation. I take it further that matching is a necessary condition in the agency of mental awareness and that it operates in a similar way during both the waking state and dreaming.
Predictors of Children's Understandings of Death: Age, Cognitive Ability, Death Experience and Maternal Communicative Competence
Authors: Hunter Sally B. , Smith Delores E.
Published: June 2008

A child's age, cognitive ability, and exposure to death in the environment have been documented as major factors affecting the formation of a mature death concept. The present study investigated the relationships between these three factors (age, cognitive ability, and death experience) and children's understandings of death, as well as the relationship between mothers' communicative competence and children's understandings of death. Thirty-seven children (ages 48–96 months) completed three cognitive tasks and answered four dichotomous questions about death. Their mothers ( N = 37) responded in writing to 16 questions about death that children are likely to ask. Results showed significant relationships between age and understanding, between seriation ability and understanding, and between death experience and understanding. There was no statistically significant relationship between maternal response competence and children's understandings of death. Implications are discussed.
African Americans in Bereavement: Grief as a Function of Ethnicity
Authors: Laurie Anna , Neimeyer Robert A.
Published: June 2008

Few empirical studies have explored the grieving process among different ethnic groups within the United States, and very little is known about how African Americans and Caucasians may differ in their experience of loss. The purpose of this study was to examine the African-American experience of grief, with particular emphasis on issues of identity change, interpersonal dimensions of the loss, and continuing attachments with the deceased. Participants were 1,581 bereaved college students (940 Caucasians and 641 African Americans) attending classes at a large southern university. Each participant completed the Inventory of Complicated Grief-Revised, the Continuing Bonds Scale, and questions regarding the circumstances surrounding his or her loss. Results revealed that African Americans experienced more frequent bereavement by homicide, maintenance of a stronger continuing bond with the deceased, greater grief for the loss of extended kin beyond the immediate family, and a sense of support in their grief, despite their tendency to talk less with others about the loss or seek professional support for it. Overall, African Americans reported higher levels of complicated grief symptoms than Caucasians, especially when they spent less time speaking to others about their loss experience. Implications of these findings for bereavement support services for African Americans were briefly noted.
The Reliability and Validity of Revised Collett—Lester Fear of Death Scale (Version 3) in a Nigerian Population
Authors: Kolawole Mosaku S. , Olusegun Ajenifuja Ko
Published: June 2008

The purpose of the study was to assess the reliability and validity of the Collett—Lester Fear of Death Scale in a Nigerian population. A cross-sectional survey was conducted among medical students using the Collett—Lester fear of death questionnaire, demographic variables were also obtained. A total of 175 students completed the questionnaire. Reliability score was good and convergent validity was also good. We concluded that the scale has good validity and reliability score among this population.
Formation of Composite Endothelial Cell–Mesenchymal Stem Cell Islets
Authors: Johansson Ulrika , Rasmusson Ida , Niclou Simone P. , Forslund Naomi , Gustavsson Linda , Nilsson Bo , Korsgren Olle , Magnusson Peetra U.
Published: June 2008

OBJECTIVE—Mesenchymal stem cells (MSCs) contribute to endothelial cell (EC) migration by producing proteases, thereby paving the way into the tissues for ECs. MSCs were added to our previously described composite EC islets as a potential means to improve their capacity for islet angiogenesis.

RESEARCH DESIGN AND METHODS—Human islets were coated with primary human bone marrow–derived MSCs and dermal microvascular ECs. The capacity of ECs, with or without MSCs, to adhere to and grow into human islets was analyzed. The survival and functionality of these composite islets were evaluated in a dynamic perifusion assay, and their capacity for angiogenesis in vitro was assessed in a three-dimensional fibrin gel assay.

RESULTS—ECs proliferated after culture in MSC-conditioned medium, and MSCs improved the EC coverage threefold compared with EC islets alone. Islet survival in vitro and the functionality of the composite islets after culture were equal to those of control islets. The EC-MSC islets showed a twofold increase in total sprout formation compared with EC islets, and vascular sprouts emanating from the EC-MSC–islet surface showed migration of ECs into the islets and also into the surrounding matrix, either alone or in concert with MSCs.

CONCLUSIONS—EC proliferation, sprout formation, and ingrowth of ECs into the islets were enhanced by MSCs. The use of composite EC-MSC islets may have beneficial effects on revascularization and immune regulation. The technique presented allows for pretreatment of donor islets with recipient-derived ECs and MSCs as a means of improving islet engraftment.
Switching-On Survival and Repair Response Programs in Islet Transplants by Bone Marrow–Derived Vasculogenic Cells
Authors: Miller Robyn , Cirulli Vincenzo , Diaferia Giuseppe R. , Ninniri Stefania , Hardiman Gary , Torbett Bruce E. , Benezra Robert , Crisa Laura
Published: June 2008

OBJECTIVE—Vascular progenitors of bone marrow origin participate to neovascularization at sites of wound healing and transplantation. We hypothesized that the biological purpose of this bone marrow–derived vascular component is to contribute angiogenic and survival functions distinct from those provided by the local tissue-derived vasculature.

RESEARCH DESIGN AND METHODS AND RESULTS—To address this hypothesis, we investigated the functional impact of bone marrow–derived vascular cells on pancreatic islets engraftment using bone marrow–reconstituted Id1+/−Id3−/− mice, a model of bone marrow–derived vasculogenesis. We show that, in this model, bone marrow–derived vasculogenic cells primarily contribute to the formation of new blood vessels within islet transplants. In contrast, graft revascularization in a wild-type background occurs by tissue-derived blood vessels only. Using these distinct transplant models in which bone marrow–and tissue-derived vasculature are virtually mutually exclusive, we demonstrate that bone marrow–derived vasculogenic cells exhibit enhanced angiogenic functions and support prompt activation of islets survival pathways, which significantly impact on islets engraftment and function. Moreover, gene profiling of vascular and inflammatory cells of the grafts demonstrate that neovascularization by bone marrow–derived cells is accompanied by the activation of a genetic program uniquely tuned to downregulate harmful inflammatory responses and to promote tissue repair.

CONCLUSIONS—These studies uncover the biological significance of bone marrow–derived vasculogenic cells in the response to injury during transplantation. Enhancing the contribution of bone marrow–derived vasculogenic cells to transplantation sites may help to overcome both limited angiogenic responses of the adult tissue-derived vasculature and untoward effects of inflammation on transplant engraftment.
Gpr40 Is Expressed in Enteroendocrine Cells and Mediates Free Fatty Acid Stimulation of Incretin Secretion
Authors: Edfalk Sara , Steneberg Pär , Edlund Helena
Published: June 2008

OBJECTIVE—The G-protein–coupled receptor Gpr40 is expressed in β-cells where it contributes to free fatty acid (FFA) enhancement of glucose-stimulated insulin secretion (1–4). However, other sites of Gpr40 expression, including the intestine, have been suggested. The transcription factor IPF1/PDX1 was recently shown to bind to an enhancer element within the 5′-flanking region of Gpr40 (5), implying that IPF1/PDX1 might regulate Gpr40 expression. Here, we addressed whether 1) Gpr40 is expressed in the intestine and 2) Ipf1/Pdx1 function is required for Gpr40 expression.

RESEARCH DESIGN AND METHODS—In the present study, Gpr40 expression was monitored by X-gal staining using Gpr40 reporter mice and by in situ hybridization. Ipf1/Pdx1-null and β-cell specific mutants were used to investigate whether Ipf1/Pdx1 controls Gpr40 expression. Plasma insulin, glucose-dependent insulinotropic polypeptide (GIP), glucagon-like peptide-1 (GLP-1), and glucose levels in response to acute oral fat diet were determined in Gpr40 mutant and control mice.

RESULTS—Here, we show that Gpr40 is expressed in endocrine cells of the gastrointestinal tract, including cells expressing the incretin hormones GLP-1 and GIP, and that Gpr40 mediates FFA-stimulated incretin secretion. We also show that Ipf1/Pdx1 is required for expression of Gpr40 in β-cells and endocrine cells of the anterior gastrointestinal tract.

CONCLUSIONS—Together, our data provide evidence that Gpr40 modulates FFA-stimulated insulin secretion from β-cells not only directly but also indirectly via regulation of incretin secretion. Moreover, our data suggest a conserved role for Ipf1/Pdx1 and Gpr40 in FFA-mediated secretion of hormones that regulate glucose and overall energy homeostasis.
Pyruvate Dehydrogenase Kinase 4
Authors: Cadoudal Thomas , Distel Emilie , Durant Sylvie , Fouque Françoise , Blouin Jean-Marc , Collinet Martine , Bortoli Sylvie , Forest Claude , Benelli Chantal
Published: June 2008

OBJECTIVE—Pyruvate dehydrogenase complex (PDC) serves as the metabolic switch between glucose and fatty acid utilization. PDC activity is inhibited by PDC kinase (PDK). PDC shares the same substrate, i.e., pyruvate, as glyceroneogenesis, a pathway controlling fatty acid release from white adipose tissue (WAT). Thiazolidinediones activate glyceroneogenesis. We studied the regulation by rosiglitazone of PDK2 and PDK4 isoforms and tested the hypothesis that glyceroneogenesis could be controlled by PDK.

RESEARCH DESIGN AND METHODS—Rosiglitazone was administered to Zucker fa/fa rats, and then PDK4 and PDK2 mRNAs were examined in subcutaneous, periepididymal, and retroperitoneal WAT, liver, and muscle by real-time RT-PCR. Cultured WAT explants from humans and rats and 3T3-F442A adipocytes were rosiglitazone-treated before analyses of PDK2 and PDK4 mRNA and protein. Small interfering RNA (siRNA) was transfected by electroporation. Glyceroneogenesis was determined using [1-14C]pyruvate incorporation into lipids.

RESULTS—Rosiglitazone increased PDK4 mRNA in all WAT depots but not in liver and muscle. PDK2 transcript was not affected. This isoform selectivity was also found in ex vivo–treated explants. In 3T3-F442A adipocytes, Pdk4 expression was strongly and selectively induced by rosiglitazone in a direct and transcriptional manner, with a concentration required for half-maximal effect at 1 nmol/l. The use of dichloroacetic acid or leelamine, two PDK inhibitors, or a specific PDK4 siRNA demonstrated that PDK4 participated in glyceroneogenesis, therefore altering nonesterified fatty acid release in both basal and rosiglitazone-activated conditions.

CONCLUSIONS—These data show that PDK4 upregulation in adipocytes participates in the hypolipidemic effect of thiazolidinediones through modulation of glyceroneogenesis.
The Equations of the Rolling Resistance of a Tire Rolling on a Drum
Authors: Hublau V. , Barillier A.
Published: June 2008

This article attempts to write a mechanical justification of the ISO 18164 norm from a mathematical point of view. There are only minor differences between the final equations and the ones used in the norm. Indeed, this work is a formal derivation of what is already known.

The main point of this article is a proper writing of the first law of thermodynamics.

The main difference between physical equations and the ones used in the ISO 18164 standard is that the norm neglects the variations of the bearing friction of the tire and of the drum between the skim test and the loaded one. The order of magnitude of the bearing friction term is approximately 0.1 kg∕t at 80 km∕h.
Ugi products containing boronate esters
Authors: Appoh Francis , Manning Marcy , Gullon Teri , Hansen Margaret , Bevans Emily , Hogan Krista , Turner Courtney , Vogels Christopher , Decken Andreas , Westcott Stephen
Published: June 2008

The Ugi reaction with formylphenylboronic acid derivatives as the carbonyl component proceeds to give the corresponding boron-containing dipeptide derivatives (Ugi products) in good yields.
Molecular machines operated by light
Authors: Credi Alberto , Venturi Margherita
Published: June 2008

The bottom-up construction and operation of machines and motors of molecular size is a topic of great interest in nanoscience, and a fascinating challenge of nanotechnology. Researchers in this field are stimulated and inspired by the outstanding progress of molecular biology that has begun to reveal the secrets of the natural nanomachines which constitute the material base of life. Like their macroscopic counterparts, nanoscale machines need energy to operate. Most molecular motors of the biological world are fueled by chemical reactions, but research in the last fifteen years has demonstrated that light energy can be used to power nanomachines by exploiting photochemical processes in appropriately designed artificial systems. As a matter of fact, light excitation exhibits several advantages with regard to the operation of the machine, and can also be used to monitor its state through spectroscopic methods. In this review we will illustrate the design principles at the basis of photochemically driven molecular machines, and we will describe a few examples based on rotaxane-type structures investigated in our laboratories.
Generalized linear Schrödinger equations and their Darboux transformations
Authors: Schulze-Halberg Axel
Published: June 2008

We construct explicit Darboux transformations of arbitrary order for a class of generalized, linear Schrödinger equations. Our construction contains the well-known Darboux transformations for Schrödinger equations with position-dependent mass, Schrödinger equations coupled to a vector potential and Schrödinger equations for weighted energy.
Conformity and Resistance: Preparing a Francophone Sporting Event in North America
Authors: Parent Milena M. , Slack Trevor
Published: June 2008

Organizing committees of large-scale sporting events face conflicting pressures from their environment when preparing to host the events, thereby leading them to conform to certain pressures and resist others. Writers on organizations, primarily institutional theorists, have mainly
examined conformity, not resistance. This article seeks to examine the competing conforming and resistance pressures for an organizing committee. Findings from a case study relating to the Jeux de la Francophonie, or Games of La Francophonie, highlighted the presence of conflicting
pressures between the North American context of the organizing committee and the European, Francophonie context of the event's international body, which impacted goal setting, funding/commercialization, athlete/artist caliber, sanctioning, and international government relationship and VIP
treatment. The nature of the event, the stakeholders involved, and the event's setting or context were found to be interrelated sources of pressures on the organizing committee.
Differences in Arts Festival Visitors Based on Level of Past Experience
Authors: Wooten Marian H. , Norman William C.
Published: June 2008

This study examined differences in visitors to the Kentuck Festival of the Arts based on past experience (i.e., number of past visits) at the festival. Two groups of visitors were identified: First-Timers (who visited for the first time in 2005) and Repeaters (who had visited multiple
times, including 2005). Visitors were compared based on demographic characteristics, travel characteristics, motivations for attendance, and perceived authenticity or uniqueness of festival products. Visitor groups did not differ with respect to demographics (except sex), but they did differ
based on travel characteristics, with First-Timers taking the longest trips to attend. As indicated in past studies, analysis of motivations revealed that socialization was found to be more important to visitors with past experience than first-time visitors. Perceptions of product uniqueness
did not differ significantly between First-Timers and Repeaters; however, both First-Timers and Repeaters did feel that festival products could not be obtained in certain retail venues, indicating they were conscious of some level of product uniqueness. Thus, findings indicated that both social
opportunities and unique products could be employed as marketing tools.
Synergistic Interface Platforms: Designing Superhydrophilic Conductive Nanoparticle‐Decorated Nanofibrous Membranes
Authors: Keirouz Antonios , Jungwirth Ute , Graf Arthur , Leese Hannah S.
Published: April 2024

In today's technological landscape, advancing methods for producing conductive membranes that simplify and streamline the development of advanced interface materials is crucial. This study introduces a versatile and innovative method for fabricating superhydrophilic, conductive nanofibrous membranes based on the in situ synthesis of polypyrrole nanoparticles on poly(vinylidene fluoride‐co‐hexafluoropropylene) (PVDF‐HFP) electrospun fibers. The composite membranes morphologically exhibit a particle‐decorated nanofibrous configuration, with polypyrrole nanoparticles distributed along the individual fibers' surface. The nanoparticle‐nanofiber configuration shows distinctive properties; electrochemically, the electrospun mats demonstrate excellent inherent electrical conductivity, good cyclic and high electrochemical stability, and low resistance. Furthermore, the amphiphilic and superhydrophilic behavior, achieved through nanotopography, porosity and interactions between the intrinsically conductive polymer and the PVDF‐HFP fibers, enables efficient uptake of polar and nonpolar analytes. The membranes also demonstrate good in vitro cell viability of both murine and human fibroblasts. Given its efficient interaction with liquids and omnidirectional 360‐degree conductivity, this material emerges as an excellent candidate for use as a biocompatible, multifunctional interface layer. The produced nanoparticle‐nanofibrous membrane materials offer a promising platform for interface applications, featuring enhanced spatiotemporal configurations and wide‐ranging applicability.
Polylactic acid/epoxidized linseed oil/polypropylene grafted maleic anhydride: A promising combination of toughness and rigidity
Authors: Cordeiro Elisangela , Gabino Alessandra A. P. , Henriques Ruan R. , Soares Bluma G.
Published: April 2024

Increasing toughness of brittle polymer without losing modulus of elasticity and tensile strength is highly important for enlarging the range of applications. In this study, polylactic acid (PLA) modified with epoxidized linseed oil (ELO) and polypropylene‐grafted maleic anhydride (PPgMA) with a good balance of toughness and rigidity was successfully prepared by melt mixing procedure. The addition of PPgMA/ELO with appropriate proportions (3:1, 5:1, and 5:5 wt%) resulted in PLA modified samples with significant ductility improvement (around 2200% of elongation at break and 1800% of tensile toughness compared to the neat PLA) with low decrease in Young modulus and tensile strength. This feature was attributed to improved interfacial interactions and the formation of crosslinked structures at the interface that also increased viscosity of the melting system and cold crystallization temperature of PLA. The scanning electron microscopy revealed the presence of small domains of modified systems. The effectiveness of reactive compatibilization among the components was also suggested by Fourier transform infrared (FTIR) spectroscopy and thermal degradation analysis. The combination of toughness, modulus of elasticity and good thermal properties make this low‐cost and scalable eco‐friendly material a promising candidate for use as biodegradable plastic in several fields including medical applications and packaging.
Exploring the substrate spectrum of phylogenetically distinct bacterial polyesterases
Authors: Makryniotis Konstantinos , Nikolaivits Efstratios , Taxeidis George , Nikodinovic‐Runic Jasmina , Topakas Evangelos
Published: April 2024

The rapid escalation of plastic waste accumulation presents a significant threat of the modern world, demanding an immediate solution. Over the last years, utilization of the enzymatic machinery of various microorganisms has emerged as an environmentally friendly asset in tackling this pressing global challenge. Thus, various hydrolases have been demonstrated to effectively degrade polyesters. Plastic waste streams often consist of a variety of different polyesters, as impurities, mainly due to wrong disposal practices, rendering recycling process challenging. The elucidation of the selective degradation of polyesters by hydrolases could offer a proper solution to this problem, enhancing the recyclability performance. Towards this, our study focused on the investigation of four bacterial polyesterases, including DaPUase, IsPETase, PfPHOase, and Se1JFR, a novel PETase‐like lipase. The enzymes, which were biochemically characterized and structurally analyzed, demonstrated degradation ability of synthetic plastics. While a consistent pattern of polyesters’ degradation was observed across all enzymes, Se1JFR stood out in the degradation of PBS, PLA, and polyether PU. Additionally, it exhibited comparable results to IsPETase, a benchmark mesophilic PETase, in the degradation of PCL and semi‐crystalline PET. Our results point out the wide substrate spectrum of bacterial hydrolases and underscore the significant potential of PETase‐like enzymes in polyesters degradation.
Political power differential and forced CEO turnover: Evidence from Chinese non‐state‐owned enterprises
Authors: Zhang Xingyi , Wang Qingfeng , Liu Weimin
Published: April 2024

In China, the prevalence of strong political connections among a significant number of boards of directors and CEOs highlights the importance of cultivating such relationships. This is particularly relevant when considering the Chinese political system where officers holding higher political ranks wield dominant, or even absolute, power in decision‐making. Our findings reveal that the political power differential (PPD) between a board of directors and its CEO plays a pivotal role in mitigating CEO entrenchment associated with political power. Specifically, when directors possess more political power than their CEOs, they can effectively fulfil their disciplinary role, leading to the dismissal of underperforming CEOs. Our study substantiates a significantly positive relationship between PPD and the probability of a forced CEO turnover, as well as the sensitivity of CEO turnover to performance. Notably, as PPD increases by one standard deviation from its mean level, we observe an approximate 30% increase in CEO turnover‐performance sensitivity. These findings confirm a higher likelihood of replacing underperforming CEOs in firms with a politically powerful board. Our results also highlight that a higher proportion of either independent or female directors alone does not guarantee effective monitoring. The key lies in ensuring that these directors possess stronger political power than the CEO.
Targeted therapies for HPV‐associated cervical cancer: Harnessing the potential of exosome‐based chipsets in combating leukemia and HPV‐mediated cervical cancer
Authors: Maitra Swastika , Mukerjee Nobendu , Alharbi Hanan M. , Ghosh Arabinda , Alexiou Athanasios , Thorat Nanasaheb D.
Published: April 2024

Exosomes play a crucial role in intercellular communication and have emerged as significant vehicles for transporting disease‐specific biomarkers. This feature provides profound insights into the progression of diseases and the responses of patients to treatments. For example, in leukemia, exosomes convey critical information through the carriage of specific proteins and nucleic acids. In the case of human papillomavirus (HPV)‐mediated cervical cancer, exosomes are particularly useful for noninvasive detection as they transport high‐risk HPV DNA and specific biomolecules, which can be indicators of the disease. Despite their vast potential, there are several challenges associated with the use of exosomes in medical diagnostics. These include their inherent heterogeneity, the need for enhanced sensitivity in detection methods, the establishment of standardization protocols, and the requirement for cost‐effective scalability in their application. Addressing these challenges is crucial for the effective implementation of exosome‐based diagnostics. Future research and development are geared towards overcoming these obstacles. Efforts are concentrated on refining the processes of biomarker discovery, establishing comprehensive regulatory frameworks, developing convenient point‐of‐care devices, exploring methods for multimodal detection, and conducting extensive clinical trials. The ultimate goal of these efforts is to inaugurate a new era of precision diagnostics within healthcare. This would significantly improve patient outcomes and reduce the burden of diseases such as leukemia and HPV‐mediated cervical cancer. The integration of exosomes with cutting‐edge technology holds the promise of significantly reinforcing the foundations of healthcare, leading to enhanced diagnostic accuracy, better disease monitoring, and more personalized therapeutic approaches.
Poly(ionic liquid)s‐Based Thermal‐Responsive Microgel for Use as SERS Substrates with “ON–OFF” Switchable Effect
Authors: Chen Yaxian , Wang Huiting , Wan Yu , Li Shun , Zhang Ling , Xing Zhiqiang , Zhang, Qian , Xia Lixin
Published: April 2024

A temperature‐responsive surface‐enhanced Raman scattering (SERS) substrate with “ON–OFF” switching based on poly(ionic liquid)s (PILs) block copolymer microgels have been designed and synthesized. The PIL units act as a joint component to anchor the gold nanoparticles (AuNPs) and analytes onto poly(N‐isopropylacrylamide) (PNIPAm). This anchor allows the analytes to be fixed at the formed hot spots under temperature stimulus. Owing to the regulation of the PNIPAm segment, the SERS substrates exhibit excellent thermally responsive SERS activity with a reversible “ON–OFF” effect. Additionally, because of the anion exchange of PILs, microgels can introduce new analytes, which offers more flexibility for the system. The substrate shows excellent reversibility, controllability, and flexibility of SERS activity, which is expected to have a broad application in the field of practical SERS sensors.