bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation of distal symmetric polyneuropathy: The role of autonomic testing, nerve biopsy, and skin biopsy (an evidence‐based review)
Authors: England J.D. , Gronseth G.S. , Franklin G. , Carter G.T. , Kinsella L.J. , Cohen J.A. , Asbury A.K. , Szigeti K. , Lupski J.R. , Latov N. , Lewis R.A. , Low P.A. , Fisher M.A. , Herrmann D. , Howard J.F. , Lauria G. , Miller R.G. , Polydefkis M. , Sumner A.J. ,   American Academy of Neurology,   American Association of Neuromuscular and Electrodiagnostic Medicine,   American Academy of Physical Medicine and Rehabilitation
Published: December 2008

Distal symmetric polyneuropathy (DSP) is the most common variety of neuropathy. Since the evaluation of this disorder is not standardized, the available literature was reviewed to provide evidence‐based guidelines regarding the role of autonomic testing, nerve biopsy, and skin biopsy for the assessment of polyneuropathy. A literature review using MEDLINE, EMBASE, Science Citation Index, and Current Contents was performed to identify the best evidence regarding the evaluation of polyneuropathy published between 1980 and March 2007. Articles were classified according to a four‐tiered level of evidence scheme and recommendations were based on the level of evidence. (1) Autonomic testing may be considered in the evaluation of patients with polyneuropathy to document autonomic nervous system dysfunction (Level B). Such testing should be considered especially for the evaluation of suspected autonomic neuropathy (Level B) and distal small fiber sensory polyneuropathy (SFSN) (Level C). A battery of validated tests is recommended to achieve the highest diagnostic accuracy (Level B). (2) Nerve biopsy is generally accepted as useful in the evaluation of certain neuropathies as in patients with suspected amyloid neuropathy, mononeuropathy multiplex due to vasculitis, or with atypical forms of chronic inflammatory demyelinating polyneuropathy (CIDP). However, the literature is insufficient to provide a recommendation regarding when a nerve biopsy may be useful in the evaluation of DSP (Level U). (3) Skin biopsy is a validated technique for determining intraepidermal nerve fiber (IENF) density and may be considered for the diagnosis of DSP, particularly SFSN (Level C). There is a need for additional prospective studies to define more exact guidelines for the evaluation of polyneuropathy. Muscle Nerve 39: 106–115, 2009
An ADI Petrov–Galerkin method with quadrature for parabolic problems
Authors: Bialecki B. , Ganesh M. , Mustapha K.
Published: December 2008

We propose and analyze a fully discrete Laplace modified alternating direction implicit quadrature Petrov–Galerkin (ADI‐QPG) method for solving parabolic initial‐boundary value problems on rectangular domains. We prove optimal order convergence results for a restricted class of the associated elliptic operator and demonstrate accuracy of our scheme with numerical experiments for some parabolic problems with variable coefficients.© 2008 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2009
An efficient TVD‐WENO method for conservation laws
Authors: Zahran Yousef Hashem
Published: December 2008

In this article, we present a high‐resolution hybrid scheme for solving hyperbolic conservation laws in one and two dimensions. In this scheme, we use a cheap fourth order total variation diminishing (TVD) scheme for smooth region and expensive seventh order weighted nonoscillatory (WENO) scheme near discontinuities. To distinguish between the smooth parts and discontinuities, we use an efficient adaptive multiresolution technique. For time integration, we use the third order TVD Runge‐Kutta scheme. The accuracy of the resulting hybrid high order scheme is comparable with these of WENO, but with significant decrease of the CPU cost. Numerical demonstrates that the proposed scheme is comparable to the high order WENO scheme and superior to the fourth order TVD scheme. Our scheme has the added advantage of simplicity and computational efficiency. Numerical tests are presented which show the robustness and effectiveness of the proposed scheme.© 2008 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2009
A secular equation for the Jacobian matrix of certain multispecies kinematic flow models
Authors: Donat Rosa , Mulet Pep
Published: December 2008

Multispecies kinematic flow models lead to nonlinear systems of conservation laws with a possibly large number of unknowns, the concentrations or the densities of the different species. In recent years, the hyperbolic character of several of these models has been analyzed by considering the characteristic polynomial of the Jacobian matrix of the system. This analysis can be considerably simplified by realizing that the fluxes in these models have a particular algebraic structure that can be exploited within a systematic algebraic framework. The framework can serve to determine the eigenvalues, and even the eigenvectors, of the Jacobian matrix of the system, which allows the use of characteristic‐based high‐resolution shock capturing schemes in numerical simulations.© 2008 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2010
Influence of alkoxy tail length and unbalanced mesogenic core on phase behavior of mesogen‐jacketed liquid crystalline polymers
Authors: Chen Si , Zhang Lan‐Ying , Gao Long‐Cheng , Chen Xiao‐Fang , Fan Xing‐He , Shen Zhihao , Zhou Qi‐Feng
Published: December 2008

When the flexible terminal substituent changes from butoxy to hexyloxy or longer, smectic C (SC) liquid crystalline phase was firstly reported to develop from a kind of mesogen‐jacketed liquid crystalline polymer (MJLCP) whose mesogenic side groups are unbalancedly bonded to the main chain without spacers. A series of MJLCPs, poly[4,4′‐bis(4‐alkoxyphenyl)‐2‐vinylbiphenyl(carboxide)] (nC2Vp, n is the number of the carbons in the alkoxy groups, n = 2, 4, 6, 8, 10, and 12) were designed and synthesized successfully via free radical polymerization. The molecular weights of the polymers were characterized with gel permeation chromatography, and the liquid crystalline properties were investigated by differential scanning calorimetry, polarized light microscopy experiments, and 1D, 2D wide‐angle X‐ray diffraction. Comparing with the butoxy analog, the polymer with unbalanced mesogenic core and shorter flexible substituents (n = 2, 4) keeps the same smectic A (SA) phase, but other polymers with longer terminal flexible substituents (n = 6, 8, 10, and 12) can develop into a well‐defined SC phase instead of SA phase. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 505–514, 2009
Dendrimers in thiol‐ene crosslinked networks and the effect of subsequent generations on thermoset properties
Authors: Nilsson Camilla , Malmström Eva , Johansson Mats , Trey Stacy M.
Published: December 2008

A series of well‐defined allyl‐ether functionalized polyester dendrimers has been synthesized via the divergent approach using traditional esterification reactions. Two commercially available trifunctional thiols, trimethylolpropane tri(3‐mercaptopropanoate) (TRIS) and ethoxylated trimethylolpropane tri(3‐mercaptopropanoate) (ETTMP), were incorporated with the dendrimers into the thiol‐ene polymer networks. The thiol‐ene reactions were conducted at room temperature and cured by UV light without the addition of photoinitiatior. Highly crosslinked films were obtained and characterized with respect to mechanical (DMA) and thermal (DSC and TGA) properties. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 589–601, 2009
An unusually small dimer interface is observed in all available crystal structures of cytosolic sulfotransferases
Authors: Weitzner Brian , Meehan Thomas , Xu Qifang , Dunbrack Roland L.
Published: December 2008

Cytosolic sulfotransferases catalyze the sulfonation of hormones, metabolites, and xenobiotics. Many of these proteins have been shown to form homodimers and heterodimers. An unusually small dimer interface was previously identified by Petrotchenko et al. (FEBS Lett 2001;490:39–43) by cross‐linking, protease digestion, and mass spectrometry and verified by site‐directed mutagenesis. Analysis of the crystal packing interfaces in all 28 available crystal structures consisting of 17 crystal forms shows that this interface occurs in all of them. With a small number of exceptions, the publicly available databases of biological assemblies contain either monomers or incorrect dimers. Even crystal structures of mouse SULT1E1, which is a monomer in solution, contain the common dimeric interface, although distorted and missing two important salt bridges. Proteins 2009. © 2008 Wiley‐Liss, Inc.
Accurate domain identification with structure‐anchored hidden Markov models, saHMMs
Authors: Tångrot Jeanette E. , Kågström Bo , Sauer Uwe H.
Published: December 2008

The ever increasing speed of DNA sequencing widens the discrepancy between the number of known gene products, and the knowledge of their function and structure. Proper annotation of protein sequences is therefore crucial if the missing information is to be deduced from sequence‐based similarity comparisons. These comparisons become exceedingly difficult as the pairwise identities drop to very low values. To improve the accuracy of domain identification, we exploit the fact that the three‐dimensional structures of domains are much more conserved than their sequences. Based on structure‐anchored multiple sequence alignments of low identity homologues we constructed 850 structure‐anchored hidden Markov models (saHMMs), each representing one domain family. Since the saHMMs are highly family specific, they can be used to assign a domain to its correct family and clearly distinguish it from domains belonging to other families, even within the same superfamily. This task is not trivial and becomes particularly difficult if the unknown domain is distantly related to the rest of the domain sequences within the family. In a search with full length protein sequences, harbouring at least one domain as defined by the structural classification of proteins database (SCOP), version 1.71, versus the saHMM database based on SCOP version 1.69, we achieve an accuracy of 99.0%. All of the few hits outside the family fall within the correct superfamily. Compared to Pfam_ls HMMs, the saHMMs obtain about 11% higher coverage. A comparison with BLAST and PSI‐BLAST demonstrates that the saHMMs have consistently fewer errors per query at a given coverage. Within our recommended E‐value range, the same is true for a comparison with SUPERFAMILY. Furthermore, we are able to annotate 232 proteins with 530 nonoverlapping domains belonging to 102 different domain families among human proteins labelled “unknown” in the NCBI protein database. Our results demonstrate that the saHMM database represents a versatile and reliable tool for identification of domains in protein sequences. With the aid of saHMMs, homology on the family level can be assigned, even for distantly related sequences. Due to the construction of the saHMMs, the hits they provide are always associated with high quality crystal structures. The saHMM database can be accessed via the FISH server at http://babel.ucmp.umu.se/fish/. Proteins 2009. © 2008 Wiley‐Liss, Inc.
Action following the discovery of a global association between the whole genome and adverse event risk in a clinical drug‐development programme
Authors: Whitehead John , Kelly Patrick , Zhou Yinghui , Stallard Nigel , Thygesen Helene , Bowman Clive
Published: December 2008

Observation of adverse drug reactions during drug development can cause closure of the whole programme. However, if association between the genotype and the risk of an adverse event is discovered, then it might suffice to exclude patients of certain genotypes from future recruitment. Various sequential and non‐sequential procedures are available to identify an association between the whole genome, or at least a portion of it, and the incidence of adverse events. In this paper we start with a suspected association between the genotype and the risk of an adverse event and suppose that the genetic subgroups with elevated risk can be identified. Our focus is determination of whether the patients identified as being at risk should be excluded from further studies of the drug. We propose using a utility function to determine the appropriate action, taking into account the relative costs of suffering an adverse reaction and of failing to alleviate the patient's disease. Two illustrative examples are presented, one comparing patients who suffer from an adverse event with contemporary patients who do not, and the other making use of a reference control group. We also illustrate two classification methods, LASSO and CART, for identifying patients at risk, but we stress that any appropriate classification method could be used in conjunction with the proposed utility function. Our emphasis is on determining the action to take rather than on providing definitive evidence of an association. Copyright © 2008 John Wiley & Sons, Ltd.
Pharmaceutical cleaning validation using non‐proximate large‐area desorption electrospray ionization mass spectrometry
Authors: Soparawalla Santosh , Salazar Gary A. , Perry Richard H. , Nicholas Mark , Cooks R. Graham
Published: December 2008

Desorption electrospray ionization (DESI) is a droplet‐based ionization method that is applied to samples in the ambient environment with little or no sample preparation. Its utility for industrial applications is explored here for the case of pharmaceutical cleaning validation. A non‐proximate large‐area DESI system was built to examine representative areas of the surfaces of reaction vessels used in active product ingredient (API) manufacturing. A large‐area sprayer capable of sampling an area of ∼2.5 cm2 was coupled with a transport tube to allow sensitive, representative sampling of APIs from a stainless steel surface 1 m away from the mass spectrometer. The system was used to detect the APIs neostigmine, acebutolol, amiloride, amiodarone, ibuprofen, montelukast, potassium clavulanate, and β‐estradiol, at levels as low as 30–10 ng/cm2, easily satisfying the general acceptable limits set by the pharmaceutical industry. These levels were achieved from surfaces resembling the equipment used in API manufacturing processes at a rate of 30 s per analysis. Copyright © 2008 John Wiley & Sons, Ltd.
Kalman filtering over wireless fading channels—How to handle packet drop
Authors: Mostofi Yasamin , Murray Richard M.
Published: December 2008

In this paper we consider estimation of dynamical systems over wireless fading communication channels using a Kalman filter. We show the impact of the stochastic communication noise on the estimation process. We furthermore show how noisy packets should be handled in the receiver. More specifically, we illustrate the impact of the availability of a cross‐layer information path on the optimum receiver design. In the absence of a cross‐layer information path, it was shown that packet drop should be designed to balance information loss and communication noise in order to optimize the performance. In the presence of a cross‐layer path, we show that keeping all the packets will minimize the average estimation error covariance. We also derive the stability condition in the presence of noisy packets and show that it is independent of the shape of the communication noise variance or availability of a cross‐layer information path. Copyright © 2008 John Wiley & Sons, Ltd.
Internationalization of Chinese and Korean firms
Authors: Yang Xiaohua , Lim Yong‐taek , Sakurai Yuka , Seo Su‐yea
Published: December 2008

This article compares and contrasts the growth of Chinese and Korean multinational enterprises (MNEs). The article identifies the similarities and differences between Chinese and Korean MNEs in terms of motivations for internationalization, expansion strategies, and paths. The goal of this article is to contribute to the literature by shifting focus on host‐country conditions to home‐country conditions in explaining the drivers for firms' internationalization. We conclude that firms are motivated to expand abroad when faced with domestic competitive disadvantages resulting from absence or deficiency of one or more of Porter's Diamond attributes in their domestic market. Implications for further studies are also explored. © 2009 Wiley Periodicals, Inc.
Toxic effects of lactational exposure to 2,3,7,8‐tetrachlorodibenzo‐p‐dioxin (TCDD) on development of male reproductive system: Involvement of antioxidants, oxidants, and p53 protein
Authors: Jin Mei Hua , Hong Chang Hee , Lee Hye Young , Kang Hyo Jin , Han Sang Won
Published: December 2008

2,3,7,8‐Tetrachlorodibenzo‐p‐dioxin (TCDD) is a potent endocrine disruptor compound and induces multiple organ dysfunctions. The effect of TCDD exposure both in adults and in utero has been well established. However, little is known about the effects of TCDD acquired through mother's milk on the development of the male reproductive system. The aim of this study was to investigate the effects and mechanisms of TCDD from lactational exposure. TCDD (1 μg/kg) was administered to C57BL/6 mouse mothers for 4 days from the day of delivery. On postnatal day 30 (PND 30) and postnatal day 60 (PND 60), body weight, body length, and anogenital distance (AGD) of male offspring were measured. The weights of the testes and epididymides were also measured. Epididymides were used for sperm counts, and testes were used to measure the activity of antioxidant enzymes (SOD, CAT, GPX, GR), the parameters of oxidative stress (hydrogen peroxide, MDA), and testosterone. In addition, expression of p53 and the proapoptotic protein, Bax, were analyzed by Western blot. TCDD exposure decreased body weight, body length, and AGD in both PND 30 and PND 60 groups compared with the control group. The activity of all antioxidant enzymes at PND 60 was decreased after TCDD treatment. TCDD treatment decreased testicular testosterone levels in both the PND 30 and PND 60 groups. The expression of p53 and Bax were also upregulated by TCDD and did not return to normal levels by PND 60. These data suggest that TCDD affects development of male offspring when the mother is exposed to TCDD during lactation. In addition, oxidative stress is a major mediator of TCDD‐induced adverse effects, and p53 may play an important role in this mechanism. © 2008 Wiley Periodicals, Inc. Environ Toxicol, 2010.
Femoral neck fracture following intramedullary nailing with misplacement of an end cup: report of two cases
Authors: Grala Paweł , Mańkowski Bartosz , Kierzynka Grzegorz
Published: December 2008

Femoral neck fracture is an unusual complication of intramedullary fixation of a broken femur. We report on two cases of femoral neck fractures attributed to misplacement of an end cup and subsequent invasive maneuvers in an effort to remove it. Iatrogenic fractures of the femoral neck during or after intramedullary nailing are reported in the medical literature. Authors associate it with many possible technical mistakes performed during the procedure, yet no complications after missed end cup placement were noted. We suggest that the fractures described below were a consequence of injury to the vascular supply and bone stock of the initially intact femoral neck.
The use of circular fine wire frames for the treatment of displaced intra-articular calcaneal fractures
Authors: Mauffrey C. , Klutts P. , Seligson D.
Published: December 2008

Background

The treatment of displaced intra-articular calcaneal fractures is still controversial.

Materials and methods

Sixteen consecutive patients admitted at University Hospital with intra-articular fractures were treated with fine wire circular frames and followed up at an average of 160 days from their injuries. We focused on radiological outcome and functional outcome using a patient-based questionnaire.

Results

We had no secondary reconstruction procedures. With the numbers available, the difference between the preoperative values and the follow-up measurements for Böhler’s angle, Gissane’s angle and posterior subtalar joint space was not statistically significant (P = 0.8,P = 0.2, andP = 0.4, respectively). The standardized AAOS FAS ranged from 42 to 96, with a mean of 80 and a standard deviation of 19.

Conclusions

Fine wire circular frame is a good alternative to ORIF in displaced intra-articular calcaneal fractures, yielding good patient function, a high return-to-work rate and a low complication rate.
Synthetic peptides identify a second periplasmic site for the plug of the SecYEG protein translocation complex
Authors: Robson Alice , Carr Beatrice , Sessions Richard B. , Collinson Ian
Published: December 2008

A short helix in the centre of the SecY subunit serves as a ‘plug’ blocking the protein channel. This site must be vacated if the channel is to open and accommodate translocating protein. We have synthesised a peptide mimic of this plug, and show that it binds to E. coli SecYEG, identifying a distinct and peripheral binding site. We propose that during active translocation the plug moves to this second discrete site and chart its position. Deletion of the plug in SecY increases the stoichiometry of the peptide–SecYEG interaction by also exposing the location it occupies in the channel. Binding of the plug peptide to the channel is unaffected by SecA.
Growth arrest of Synechocystis sp. PCC6803 by superoxide generated from heterologously expressed Rhodobacter sphaeroides chlorophyllide a reductase
Authors: Kim Eui-Jin , Kim Ju-Sim , Rhee Hae Jin , Lee Jeong K.
Published: December 2008

The photosynthetic growth of Synechocystis sp. PCC6803 ceased upon expression of Rhodobacter sphaeroides chlorophyllide a reductase (COR). However, an increase in cytosolic superoxide dismutase level in the recombinant Synechocystis sp. PCC6803 completely reversed the growth cessation. This demonstrates that COR generates superoxide in Synechocystis sp. PCC6803. Considering the dissolved oxygen (DO) level suitable for COR, the intracellular DO of this oxygenic photosynthetic cell appears to be low enough to support COR‐mediated superoxide generation. The growth arrest of Synechocystis sp. PCC6803 by COR may give an insight into the evolutionary path from bacteriochlorophyll a biosynthetic pathway to chlorophyll a, which bypasses COR reaction.
Water supply: Public or private?
Authors: Pérard Edouard
Published: December 2008

Most theories on private sector participation in water infrastructure are based on the sole supposed difference of efficiency between the public and the private sector. The review of 22 empirical tests and 51 case studies shows that private sector participation per se in water supply does not systematically have a significant positive effect on efficiency. Thus, the choice between public and private water delivery is probably not only a question of efficiency.

We developed a complete theory of the choice between public and private water supply based on four components: difference of cost of funds, transaction costs of outsourcing, difference of efficiency and potential political cost of privatizing. Since determinants of the theory fluctuate over the time and depend on the local context, this theory can explain both privatization and municipalization movements as well as why some local governments outsource water supply, while others opt for direct provision.

The tests on 459 US counties in charge of water supply in 45 states provide substantial support for the theory. Significant determinants of the choice of public versus private water delivery include the cost of funds, especially the social cost of taxes, transaction costs, the difference of efficiency and the potential political cost of privatizing.

Moreover, we tested other literature's theories, which suggest employment as a motive of public provision and cost of public wages as a cause of privatization. These two arguments seem to be irrelevant.

We additionally tested the influence of ownership on the number of drinking water environmental violations and found no significance.
Dense, bounded shear flows of agitated solid spheres in a gas at intermediate Stokes and finite Reynolds numbers
Authors: XU HAITAO , VERBERG ROLF , KOCH DONALD L. , LOUGE MICHEL Y.
Published: December 2008

We consider moderately dense bounded shear flows of agitated homogeneous inelastic frictionless solid spheres colliding in a gas between two parallel bumpy walls at finite particle Reynolds numbers, volume fractions between 0.1 and 0.4, and Stokes numbers large enough for collisions to determine the velocity distribution of the spheres. We adopt a continuum model in which constitutive relations and boundary conditions for the granular phase are derived from kinetic theory, and in which the gas contributes a viscous dissipation term to the fluctuation energy of the grains. We compare its predictions to recent lattice-Boltzmann (LB) simulations. The theory underscores the role played by the walls in the balances of momentum and fluctuation energy. When particle inertia is large, the solid volume fraction is nearly uniform, thus allowing us to treat the rheology using unbounded flow theory with an effective shear rate, while predicting slip velocities at the walls. When particle inertia decreases or fluid inertia increases, the solid volume fraction becomes increasingly heterogeneous. In this case, the theory captures the profiles of volume fraction, mean and fluctuation velocities between the walls. Comparisons with LB simulations allow us to delimit the range of parameters within which the theory is applicable.
Capillary entry pressure and the leakage of gravity currents through a sloping layered permeable rock
Authors: WOODS ANDREW W. , FARCAS ADRIAN
Published: December 2008

We examine the motion of a buoyant fluid injected into a water-saturated porous rock as it spreads along a thin inclined low-permeability barrier. We account for leakage of the fluid across the barrier once the current is sufficiently deep so that the pressure exceeds the capillary threshold. We show that at some distance from the source, the pressure decreases below this threshold, and all the remaining flux spreads laterally along the barrier. We examine the controls on the partitioning of the flow between the draining flux and the laterally spreading flux and also the controls on the lateral extent of the draining region for the case of an instantaneous release and a maintained release of fluid. We consider the implications of our work for the dispersal of CO2 plumes which may be sequestered in deep saline aquifers.
Feasibility of imaging living cells at subnanometer resolutions by ultrafast X-ray diffraction
Authors: Bergh Magnus , Huldt Gösta , Tîmneanu Nicusor , Maia Filipe R. N. C. , Hajdu Janos
Published: December 2008

Detailed structural investigations on living cells are problematic because existing structural methods cannot reach high resolutions on non-reproducible objects. Illumination with an ultrashort and extremely bright X-ray pulse can outrun key damage processes over a very short period. This can be exploited to extend the diffraction signal to the highest possible resolution in flash diffraction experiments. Here we present an analysis of the interaction of a very intense and very short X-ray pulse with a living cell, using a non-equilibrium population kinetics plasma code with radiation transfer. Each element in the evolving plasma is modeled by numerous states to monitor changes in the atomic populations as a function of pulse length, wavelength, and fluence. The model treats photoionization, impact ionization, Auger decay, recombination, and inverse bremsstrahlung by solving rate equations in a self-consistent manner and describes hydrodynamic expansion through the ion sound speed. The results show that subnanometer resolutions could be reached on micron-sized cells in a diffraction-limited geometry at wavelengths between 0·75 and 1·5 nm and at fluences of 1011–1012 photons μm−2in less than 10 fs. Subnanometer resolutions could also be achieved with harder X-rays at higher fluences. We discuss experimental and computational strategies to obtain depth information about the object in flash diffraction experiments.
From numerical concepts to concepts of number
Authors: Rips Lance J. , Bloomfield Amber , Asmuth Jennifer
Published: December 2008

Many experiments with infants suggest that they possess quantitative abilities, and many experimentalists believe that these abilities set the stage for later mathematics: natural numbers and arithmetic. However, the connection between these early and later skills is far from obvious. We evaluate two possible routes to mathematics and argue that neither is sufficient: (1) We first sketch what we think is the most likely model for infant abilities in this domain, and we examine proposals for extrapolating the natural number concept from these beginnings. Proposals for arriving at natural number by (empirical) induction presuppose the mathematical concepts they seek to explain. Moreover, standard experimental tests for children's understanding of number terms do not necessarily tap these concepts. (2) True concepts of number do appear, however, when children are able to understand generalizations over all numbers; for example, the principle of additive commutativity (a+b=b+a). Theories of how children learn such principles usually rely on a process of mapping from physical object groupings. But both experimental results and theoretical considerations imply that direct mapping is insufficient for acquiring these principles. We suggest instead that children may arrive at natural numbers and arithmetic in a more top-down way, by constructing mathematical schemas.
Do mental magnitudes form part of the foundation for natural number concepts? Don't count them out yet
Authors: Barth Hilary
Published: December 2008

The current consensus among most researchers is that natural number is not built solely upon a foundation of mental magnitudes. On their way to the conclusion that magnitudes do not form any part of that foundation, Rips et al. pass rather quickly by theories suggesting that mental magnitudes might play some role. These theories deserve a closer look.
Bridging the gap between intuitive and formal number concepts: An epidemiological perspective
Authors: De Cruz Helen
Published: December 2008

The failure of current bootstrapping accounts to explain the emergence of the concept of natural numbers does not entail that no link exists between intuitive and formal number concepts. The epidemiology of representations allows us to explain similarities between intuitive and formal number concepts without requiring that the latter are directly constructed from the former.
Not all basic number representations are analog: Place coding as a precursor of the natural number system
Authors: Fias Wim , Verguts Tom
Published: December 2008

Rips et al.'s arguments for rejecting basic number representations as a precursor of the natural number system are exclusively based on analog number coding. We argue that these arguments do not apply to place coding, a type of basic number representation that is not considered by Rips et al.
Recursive reminding and children's concepts of number
Authors: Hintzman Douglas L.
Published: December 2008

According to the recursive reminding hypothesis, repetition interacts with episodic memory to produce memory representations that encode – and recursively embed – experiences of reminding. These representations provide the rememberer with a basis for differentiating among the first time something happens, the second time it happens, and so on. I argue that such representations could mediate children's understanding of natural number.
Early numerical representations and the natural numbers: Is there really a complete disconnect?
Authors: Lourenco Stella F. , Levine Susan C.
Published: December 2008

The proposal of Rips et al. is motivated by discontinuity and input claims. The discontinuity claim is that no continuity exists between early (nonverbal) numerical representations and natural number. The input claim is that particular experiences (e.g., cardinality-related talk and object-based activities) do not aid in natural number construction. We discuss reasons to doubt both claims in their strongest forms.
Learning natural numbers is conceptually different than learning counting numbers
Authors: Read Dwight
Published: December 2008

How children learn number concepts reflects the conceptual and logical distinction between counting numbers, based on a same-size concept for collections of objects, and natural numbers, constructed as an algebra defined by the Peano axioms for arithmetic. Cross-cultural research illustrates the cultural specificity of counting number systems, and hence the cultural context must be taken into account.
Precursors to number: Equivalence relations, less-than and greater-than relations, and units
Authors: Sophian Catherine
Published: December 2008

Infants' knowledge need not have the same structure as the mature knowledge that develops from it. Fundamental to an understanding of number are concepts of equivalence and less-than and greater-than relations. These concepts, together with the concept of unit, are posited to be the starting points for the development of numerical knowledge.
Dissonances in theories of number understanding
Authors: Rips Lance J. , Bloomfield Amber , Asmuth Jennifer
Published: December 2008

Traditional theories of how children learn the positive integers start from infants' abilities in detecting the quantity of physical objects. Our target article examined this view and found no plausible accounts of such development. Most of our commentators appear to agree that no adequate developmental theory is presently available, but they attempt to hold onto a role for early enumeration. Although some defend the traditional theories, others introduce new basic quantitative abilities, new methods of transformation, or new types of end states. A survey of these proposals, however, shows that they do not succeed in bridging the gap to knowledge of the integers. We suggest that a better theory depends on starting with primitives that are inherently structural and mathematical.
Semantic cognition or data mining?
Authors: Borsboom Denny , Visser Ingmar
Published: December 2008

We argue that neural networks for semantic cognition, as proposed by Rogers & McClelland (R&M), do not acquire semantics and therefore cannot be the basis for a theory of semantic cognition. The reason is that the neural networks simply perform statistical categorization procedures, and these do not require any semantics for their successful operation. We conclude that this has severe consequences for the semantic cognition views of R&M.
A crosslinguistic perspective on semantic cognition
Authors: Majid Asifa , Huettig Falk
Published: December 2008

Coherent covariation appears to be a powerful explanatory factor accounting for a range of phenomena in semantic cognition. But its role in accounting for the crosslinguistic facts is less clear. Variation in naming, within the same semantic domain, raises vexing questions about the necessary parameters needed to account for the basic facts underlying categorization.
On the semantics of infant categorization and why infants perceive horses as humans
Authors: Quinn Paul C.
Published: December 2008

This commentary considers the issues of what should be taken as evidence for semantic categorization in infants and why infants display a surprising asymmetry in the categorization of humans versus nonhuman animals. It is argued that perceptual knowledge should be viewed as a potent source of information for semantic categorization, and that the asymmetrical categorization behavior arises as a consequence of the frequency and similarity structure of experience.
A simple model from a powerful framework that spans levels of analysis
Authors: Rogers Timothy T. , McClelland James L.
Published: December 2008

The commentaries reflect three core themes that pertain not just to our theory, but to the enterprise of connectionist modeling more generally. The first concerns the relationship between a cognitive theory and an implemented computer model. Specifically, how does one determine, when a model departs from the theory it exemplifies, whether the departure is a useful simplification or a critical flaw? We argue that the answer to this question depends partially upon the model's intended function, and we suggest that connectionist models have important functions beyond the commonly accepted goals of fitting data and making predictions. The second theme concerns perceived in-principle limitations of the connectionist approach to cognition, and the specific concerns these perceived limitations raise for our theory. We argue that the approach is not in fact limited in the ways our critics suggest. One common misconception, that connectionist models cannot address abstract or relational structure, is corrected through new simulations showing directly that such structure can be captured. The third theme concerns the relationship between parallel distributed processing (PDP) models and structured probabilistic approaches. In this case we argue that there the difference between the approaches is not merely one of levels. Our PDP approach differs from structured statistical approaches at all of Marr's levels, including the characterization of the goals of cognitive computations, and of the representations and algorithms used.
Local entropy theory
Authors: GLASNER ELI , YE XIANGDONG
Published: December 2008

In this survey we offer an overview of the so-called local entropy theory, which has been in development since the early 1990s. While doing so, we emphasize the connections between the topological dynamics and the ergodic theory points of view.
Multistage volcanic events: Tephra hazard simulations for the Okataina Volcanic Center, New Zealand
Authors: Jenkins Susanna , Magill Christina , McAneney John , Hurst Tony
Published: December 2008

While volcanic events are commonly characterized by multiple eruptive stages, most probabilistic tephra hazard analyses only simulate the major (paroxysmal) stage. In this study, we reconsider this simplified treatment by comparing hazard outcomes from simulated single‐ and multistage eruption sequences, using the Okataina Volcanic Center (OVC) in New Zealand as a case study. Our study draws upon geological evidence particular to the OVC as well as generalized patterns of eruptive behavior from other analogous volcanic centers. Exceedance probabilities of simulated tephra thickness, the cumulative duration of explosive behavior, and the duration of the entire eruptive sequence were all compared. Multistage simulations show an increased hazard with the greatest differences lying close to the vent for long duration and high thickness thresholds and at intermediate distances between the vent and the maximum extent of the deposit for lower thickness and duration thresholds. Multiple explosive stages increase the likelihood of an event lasting longer than 1 month by up to sevenfold and, for given low‐probability events, accumulated tephra thicknesses in some locations may increase by 1 order of magnitude and impact up to 22% more of New Zealand's North Island. Given our understanding of the eruptive history of the Okataina Volcanic Center, multistage simulations provide a better understanding of the potential hazard from this source.
Advanced thermodynamic and processing modelling integration for amine scrubbing in post-combustion CO~2~ capture
Authors: Mac Dowell Niall , Galindo Amparo , Adjiman Claire , Jackson George
Published: December 2008

The reduction in CO~2~ emissions from anthropogenic sources has become a topic of widespread interest over the past number of years. As the power generation sector is by far the largest stationary-point-source of CO~2~, being responsible for approximately 35% of total global CO~2~ emissions^1^ this question has special relevance for this industry. As the inclusion of carbon capture facilities incurs a significant energy penalty on the efficiency coal-fired power-stations, there is a strong requirement for the improvement of these systems in terms of the minimisation of operation and maintenance costs, capital costs and the maximisation of efficiency and flexibility. This last issue has relevance for start-up times and ramp-rates. Post-combustion capture methods based on the chemisorption of CO~2~ in aqueous amine solutions are among the most mature and accepted technologies for CO2 capture from power plants^2^. However, amines are complex, associating solvents requiring a sophisticated thermodynamic model, capable of modelling the hydrogen bonding interactions that occur in these systems. One such model is provided by the statistical associating fluid theory (SAFT^3^). This is a molecular approach, specifically suited to hydrogen-bonding, chain-like fluids. In this contribution we use the SAFT approach for potentials of variable range (SAFT-VR^4^) to model the thermodynamics and phase equilibria of a number of amines including ammonia and monoethanolamine. The molecules are modelled as homonuclear chains of tangentially bonded square-well segments of variable range, and a number of short-ranged off-centre attractive square-well sites are used to mediate the anisotropic effects due to association in the fluids. We also determine values of the binary parameters for mixtures and then use these parameters to predict the phase equilibria of amine+water, amine+carbon dioxide as well as water+carbon dioxide mixtures. We then consider the phase equilibria of the ternary mixtures of amine+water+carbon dioxide and finally that of quaternary mixtures of amine+water+carbon dioxide+nitrogen. A good quantitative understanding of the phase behaviour of these quaternary mixtures is essential for accurate modelling of absorption processes for carbon dioxide capture. 1. Steeneveldt, R., Berger, B. & Torp, T.A., ChERD, 84(A9): 739-763, 20062. Rao, A.B.; Rubin, E.S., 2002. A Technical, Economic, and Environmental Assessment of Amine-Based CO2 Capture Technology for Power Plant Greenhouse Gas Control. Environ. Sci. Technol. 36, 4467-44753. Chapman, W.G., Gubbins, K.E., Jackson, G. & Radosz, M., Ind. Eng. Chem. Res., 1990. 29, 1709-17213. Gil-Villegas, A., Galindo, A., Whitehead, P. J., Mills, S. J. & Jackson, G., J. Chem. Phys. 106 (10), 8 March 1997
21 Tesla Micro-MRI of Rat Skin
Authors: Sharma Rakesh , Fulzele Suniket , Shetty Kiran , Sachdeva Mandeep , Locke Bruce
Published: December 2008

*Aim:* A rapid ultra high resolution ex vivo MRI imaging method was evaluated to visualize rat skin structure. The main objectives were:1.qualitative assessment of viable epidermis, hair, oil and fat-rich skin features by multi-contrast approach;2.achievement of spatial resolution up to 15 microns; 3.comparison of skin histology with MRI skin features obtained by 21 Tesla magnetic resonance imaging (MRI) imager. *Introduction:* The ultrawide bore 900 MHz magnet has high resolution NMR magnet has a central field of 21.1 T. The high resolution MRI technique has potential for both quantitative and non-invasive morphological evaluation at micrometer level. The MRI signal was sensitive to water protons and glycolipid distribution in the skin. At 21 Tesla, both contrast and resolution are enhanced utilizing thin slices up to 100 microns. Multiple contrast by magnetization transfer contrast (MTC), spin–lattice relaxation (T1-weighting), combination of T2 and magnetic field in-homogeneity (T2*-weighting) may provide resolution up to 15 microns with distinct proton-fat contrast.

Materials and Methods:

On histology and MRI co-registered images, skin features of epidermis, dermis, hair, sebaceous glands were compared. For spin echo(SE) and gradient echo(GE) imaging utilized the MSME_Bio and GEFC (Bruker Biospin, Billerika) methods at short TE=8 ms and TR=100,200,500,1000 ms(for T1 weighted) and TE= 8,16, 24 ms, TR=1000 ms(for T2 weighted), matrix of 256 x 256 and 0.1-0.3 mm slice thickness, NEX=4. The MSME_MTR was used for MT images. The MRI visible skin features regions were identified for epidermis, dermis, hair follicles and oil glands. Distinct epidermis and intact hair and root thickness served as good skin quality.

*Results:*

At high resolution 25 μm, SE T1-weighted images showed distinct epidermis, brighter brightest stratum corneum; brightgray papillary (collagen) and reticular dermis (glycolipids). The hair follicles and sebaceous glands appeared gray (Figure 1). Signal intensity was proportional to TR. At TE=8 ms, water and lipids appeared distinct in the dermis. The T2-weighted images highlighted the stratum corneum (dark thin band at top), viable epidermis (white band below the stratum corneum), hair follicles/sebaceous glands (light channels running vertically through the skin), and dermis (dark regions between hair follicles)(Figure 1 and Table 1). Water-fat phantom showed distinct intensity (Figure1E). In plane resolution was 100 micron and contrast enhancement was achieved by multicontrast approach. Histology-MRI comparison: Epidermis, hair root, follicles, sebaceous gland were comparable. *Conclusion:* High resolution SE short TE images demonstrate distinct contrast properties as preliminary data. High CNR and better morphology both require ultra high magnetic field using T2* weighted and magnetization transfer weighted MRI imaging to achieve high in-plane and spatial resolution.
The convergence of analytic high-β equilibrium in a finite aspect ratio tokamak
Authors: Neches R. Y. , Cowley S. C. , Gourdain P. A. , Leboeuf J. N.
Published: December 2008

The characteristics of near-unity-β equilibria are investigated with two codes. CUBE is a multigrid Grad–Shafranov solver [Gourdain et al., J. Comput. Phys. 216, 275 (2006)], and Ophidian was written to compute solutions using analytic unity-β equilibria [Cowley et al., Phys. Fluids B 3, 2066 (1991)]. Results from each method are qualitatively and quantitatively compared across a spectrum of mutually relevant parameters. These comparisons corroborate the theoretical results and provide benchmarks for high-resolution numerical results available from CUBE. Both tools facilitate the exploration of the properties of high-β equilibria, such as a highly diamagnetic plasma and its ramifications for stability and transport.
Schrödinger equation Monte Carlo in three dimensions for simulation of carrier transport in three-dimensional nanoscale metal oxide semiconductor field-effect transistors
Authors: Liu Keng-Ming , Chen Wanqiang , Register Leonard F. , Banerjee Sanjay K.
Published: December 2008

A quantum transport simulator, Schrödinger equation Monte Carlo (SEMC) in three dimensions, is presented that provides a rigorous yet reasonably computationally efficient quantum mechanical treatment of real scattering processes within quantum transport simulations of nanoscale three-dimensional (3D) metal oxide semiconductor field-effect transistor (MOSFET) geometries such as quantum wire and multigate field-effect transistors. This work represents an extension of earlier versions of SEMC for simulating quantum transport and scattering in systems with relatively simpler quasi-one-dimensional and quasi-two-dimensional geometries such as quantum-cascade lasers (via SEMC in one dimension) and silicon-on-insulator or dual-gate MOSFETs (via SEMC in two dimensions), respectively. However, the limiting computational considerations can be significantly different. The SEMC approach represents a variation in nonequilibrium Green’s function techniques with scattering as well as carrier injection into the simulation region treated via Monte Carlo techniques. Scattering mechanisms include intravalley and intervalley scatterings, intrasubband and intersubband scatterings via acoustic and optical phonons, and, in the former case, surface roughness scattering. SEMC-3D simulations of a silicon omega-gate nanoscale n-channel MOSFET are provided to illustrate the modeling technique as well as the complexity of scattering effects in such nanoscale devices.