cssi/SciSciGPT-SciSciNet huggingface dataset:
Subset Refinement for Digital Volume Correlation: Numerical and Experimental Applications

Digital image correlation (DIC) metrology has gained significant popularity over the past few decades because of its ease of use and reliable displacement measurement. Unlike other optical methods, such as for example interferometric techniques, which produce a fixed resolution depending on the particulars of the optical set-up used, key factors affecting accuracy and resolution of DIC include among others correlation point density (i.e., which pixels are selected as measurements points) and subset size (i.e., the area around the measurement pixel used in the correlation). Intuitively, following reasoning from experience with numerical techniques, a smaller correlation grid spacing and smaller subset size would be expected to produce more accurate results. However, this is not the case in DIC, thus implying that the overall accuracy of DIC metrology would benefit by selecting subset size and correlation point frequency depending on the strain field under observation. Such an adaptive parameter selection would be even more relevant when using DIC in three dimensions (termed Digital Volume Correlation, or DVC), where the computational cost is significantly increased over two-dimensional problems. Here we explore this idea of adaptive refinement by implementing a scheme for subset size selection and then applying it, first to a numerically defined test problem, and then to an actual experimental application. We investigate the relation between subset size and errors in DVC and propose an adaptivity parameter for subset refinement based on the norm of the gradient of the displacement gradient. This gradient parameter, which contains a significant amount of noise since it represents the second derivative of a discrete displacement field, is not used in a metrological sense, but only to determine areas where refinement is needed. In those areas, DVC is then re-computed with appropriately refined parameters and the results are merged with coarser analyses outside these areas. An application of the scheme to a compression experiment with a spherical inclusion in an elastic matrix is performed and shows increased result sensitivity in the region near the inclusion when parameter refinement is adaptively performed there.
GRP94: an HSP90-like protein specialized for protein folding and quality control in the Endoplasmic Reticulum

Glucose-regulated protein 94 is the HSP90-like protein in the lumen of the endoplasmic reticulum and therefore it chaperones secreted and membrane proteins. It has essential functions in development and physiology of multicellular organisms, at least in part because of this unique clientele. GRP94 shares many biochemical features with other HSP90 proteins, in particular its domain structure and ATPase activity, but also displays distinct activities, such as calcium binding, necessitated by the conditions in the endoplasmic reticulum. GRP94's mode of action varies from the general HSP90 theme in the conformational changes induced by nucleotide binding, and in its interactions with co-chaperones, which are very different from known cytosolic co-chaperones. GRP94 is more selective than many of the ER chaperones and the basis for this selectivity remains obscure. Recent development of molecular tools and functional assays has expanded the spectrum of clients that rely on GRP94 activity, but it is still not clear how the chaperone binds them, or what aspect of folding it impacts. These mechanistic questions and the regulation of GRP94 activity by other proteins and by post-translational modification differences pose new questions and present future research avenues. This article is part of a Special Issue entitled: Heat Shock Protein 90 (HSP90).
Nuclear Archeology in a Bottle: Evidence of Pre-Trinity U.S. Weapons Activities from a Waste Burial Site

During World War II, the Hanford Site in Washington became the location for U.S. plutonium production. In 2004, a bottle containing a sample of plutonium was recovered from a Hanford waste trench. Here, state-of-the-art instrumental analyses, reactor model simulations, and investigative science techniques were used to provide insights as to the origin of this unknown sample, a process collectively termed as nuclear archeology. Isotopic age dating conducted on the sample in 2007 indicated the sample was separated from the spent fuel 61.6 ± 4.5 years earlier. The isotope 22Na, a detectable product of a secondary nuclear reaction, proved useful as a powerful tool for nuclear forensic analysis as (1) an easily detectable signifier of the presence of α emitting actinides, (2) an indicator of sample splitting, and (3) a measure of the time since sample splitting. Analytical results of minor actinide isotopes and reactor model simulations confirmed the material originated from the X-10 reactor in Oak Ridge, TN. ...
Cerebrospinal fluid in multiple sclerosis.

Background: Technological advances have made it possible to examine the human cerebrospinal fluid (CSF) in a manner that was previously impossible. CSF provides a window into the changes that occur in the central nervous system (CNS) in health and disease. Through analysis of the CSF, we discern indirectly the state of health of the CNS, and correctly or incorrectly, draw conclusions regarding mechanisms of CNS injury and repair. Objective, Materials and Methods: To review the current state of knowledge of changes in the CSF in multiple sclerosis. Discussion: Establishing CSF markers that permit evaluation of the various biological processes in multiple sclerosis remains a challenge. Of all the biological processes, inflammatory markers are probably the best identified. Detection of oligoclonal immunoglobulin bands in the CSF is now established as the single most useful laboratory marker in the CSF to aid in the diagnosis of multiple sclerosis. Markers of demyelination, remyelination, neuro-axonal loss, neural repair and regeneration, and astrogliosis are only now being recognized. A good surrogate for any of these pathophysiological processes has not been defined to date. Conclusion: The goal of future research is not only to define surrogate markers in the CSF for each of the above functions, but also to extend it to other more readily accessible body fluids like blood and urine. A synopsis of the current literature in most of these areas of CSF evaluation pertaining to multiple sclerosis is presented in this article.
Direct evidence for bimetallic clusters

Direct evidence for the formation of bimetallic clusters as proposed by Sinfelt is obtained from Mossbauer spectroscopic studies of Fe and PdFe/η-Al 2 O 3 catalysts. Mossbauer spectroscopy was used to determine the chemical states of iron on η-Al 2 O 3 in the absence and presence of palladium for various reduction and oxidation treatments. Ferric ions on η-Al 2 O 3 in low concentrations (0.1%) were unaffected by H 2 or CO at room temperature and were reduced only to the ferrous state in H 2 at 973 °K or below. In PdFe/η-Al 2 O 3 catalysts, however, the iron is reduced at room temperature to the ferrous state in H 2 or CO providing evidence that the iron and palladium were already associated in the catalyst as prepared. Reduction of PdFe/η-Al 2 O 3 at 673 °K gave a catalyst with 54% dispersion and Mossbauer parameters consistent with well-dispersed PdFe bimetallic clusters. The iron in this material could be reversibly oxidized in O 2 and reduced in H 2 at room temperature—a characteristic which we attribute to iron associated with palladium. Agglomeration of PdFe/η-Al 2 O 3 in H 2 at successively higher temperatures up to 973 °K caused a fivefold decrease in dispersion from 54 to 11%. At the same time the quadrupole split Mossbauer spectrum characteristic of iron at the surface of well-dispersed PdFe clusters collapsed into a broad single line characteristic of iron “in” the agglomerated PdFe clusters. With decreasing dispersion the amount of iron which could be oxidized to the ferric state on exposing the reduced catalysts to O 2 at room temperature also decreased and “surface” and “bulk” peaks for the clusters could be resolved. The Mossbauer parameters, chemical behavior and changes in Mossbauer spectra of PdFe/η-Al 2 O 3 catalysts on agglomeration provide conclusive evidence that bimetallic clusters are formed in catalysts prepared by the usual impregnation, drying and calcination techniques.
Derived absolute rate constants for additions of ambiphilic carbenes to alkenes

Abstract Additions of methoxychlorocharbene and trifluoroethoxychlorocarbene to trans -butene occur with kabs ∼ 330 and 10,000 M−1s−1, respectively.
Diluted quantum antiferromagnets: Spin excitations and long-range order

We have studied the static and dynamic magnetic properties of two-dimensional (2D) and quasi-two-dimensional, spin-S, quantum Heisenberg antiferromagnets diluted with spinless vacancies. Using spin-wave theory and the T-matrix approximation we have calculated the staggered magnetization $M(x,T),$ the neutron scattering dynamical structure factor $\mathcal{S}(\mathbf{k},\ensuremath{\omega}),$ the 2D magnetic correlation length $\ensuremath{\xi}(x,T)$ and, for the quasi- (2D) case, the N\'eel temperature ${T}_{N}(x).$ We find that in two dimensions a hydrodynamic description of excitations in terms of spin waves breaks down at wavelengths larger than $l/a\ensuremath{\sim}{e}^{\ensuremath{\pi}/4x},$ x being the impurity concentration and a the lattice spacing. We find signatures of localization associated with the scale l, and interpret this scale as the localization length of magnons. The spectral function for momenta ${a}^{\ensuremath{-}1}\ensuremath{\gg}k\ensuremath{\gg}{l}^{\ensuremath{-}1}$ consists of two distinct parts: (i) a damped quasiparticle peak at an energy ${c}_{0}k\ensuremath{\gtrsim}\ensuremath{\omega}\ensuremath{\gg}{\ensuremath{\omega}}_{0},$ with abnormal damping ${\ensuremath{\Gamma}}_{k}\ensuremath{\sim}x{c}_{0}k,$ where ${\ensuremath{\omega}}_{0}\ensuremath{\sim}{c}_{0}{l}^{\ensuremath{-}1},$ ${c}_{0}$ is the bare spin-wave velocity; and (ii) a non-Lorentian localization peak at $\ensuremath{\omega}\ensuremath{\sim}{\ensuremath{\omega}}_{0}.$ For $k\ensuremath{\lesssim}{l}^{\ensuremath{-}1}$ these two structures merge, and the spectrum becomes incoherent. The density of states acquires a constant term, and exhibits an anomalous peak at $\ensuremath{\omega}\ensuremath{\sim}{\ensuremath{\omega}}_{0}$ associated with low-energy localized excitations. These anomalies lead to a substantial enhancement of the magnetic specific heat ${C}_{M}$ at low temperatures. Although the dynamical properties are significantly modified, we show that $D=2$ is not the lower critical dimension for this problem. We find that at small x the average staggered magnetization at the magnetic site is $M(x,0)\ensuremath{\simeq}S\ensuremath{-}\ensuremath{\Delta}\ensuremath{-}Bx,$ where $\ensuremath{\Delta}$ is the zero-point spin deviation and $B\ensuremath{\simeq}0.21$ is independent of the value of S; the N\'eel temperature ${T}_{N}(x)\ensuremath{\simeq}(1\ensuremath{-}{A}_{s}x) {T}_{N}(0),$ where ${A}_{s}=\ensuremath{\pi}\ensuremath{-}2/\ensuremath{\pi}+B/(S\ensuremath{-}\ensuremath{\Delta})$ is weakly S dependent. Our results are in quantitative agreement with recent Monte Carlo simulations and experimental data for $S=1/2,$ 1, and 5/2. In our approach long-range order persists up to a high concentration of impurities ${x}_{c}$ which is above the classical percolation threshold ${x}_{p}\ensuremath{\approx}0.41.$ This result suggests that long-range order is stable at small x, and can be lost only around $x\ensuremath{\simeq}{x}_{p}$ where approximations of our approach become invalid.
Neuronal Ubiquitin Homeostasis

Neurons have highly specialized intracellular compartments that facilitate the development and activity of the nervous system. Ubiquitination is a post-translational modification that controls many aspects of neuronal function by regulating protein abundance. Disruption of this signaling pathway has been demonstrated in neurological disorders such as Parkinson's disease, Amyotrophic Lateral Sclerosis and Angleman Syndrome. Since many neurological disorders exhibit ubiquitinated protein aggregates, the loss of neuronal ubiquitin homeostasis may be an important contributor of disease. This review discusses the mechanisms utilized by neurons to control the free pool of ubiquitin necessary for normal nervous system development and function as well as new roles of protein ubiquitination in regulating the synaptic activity.
Identification of D3 and σ receptors in the rat striatum and nucleus accumbens using (±)-7-hydroxy-N,N-Di-n-[3H]propyl-2-aminotetralin and carbetapentane

Cross-reactions between dopamine D3 and sigma receptor ligands were investigated using (+/-)-7-hydroxy-N,N-di-n-[3H]propyl-2-aminotetralin [(+/-)-7-OH-[3H]-DPAT], a putative D3-selective radioligand, in conjunction with the unlabeled sigma ligands 1,3-di(2-tolyl)guanidine (DTG), carbetapentane, and R(-)-N-(3-phenyl-1-propyl)-1-phenyl-2-aminopropane [R(-)-PPAP]. In transfected CCL1.3 mouse fibroblasts expressing the human D3 receptor, neither DTG nor carbetapentane (0.1 microM) displaced (+/-)-7-OH-[3H]DPAT binding. R(-)-PPAP (0.1 microM) displaced 39.6 +/- 1.0% of total (+/-)-7-OH-[3H]DPAT binding. In striatal and nucleus accumbens homogenates, (+/-)-7-OH-[3H]DPAT labeled a single site (15-20 fmol/mg of protein) with high (1 nM) affinity. Competition analysis with carbetapentane defined both high- and low-affinity sites in striatal (35 and 65%, respectively) and nucleus accumbens (59 and 41%, respectively) tissue, yet R(-)-PPAP identified two sites in equal proportion. Carbetapentane and R(-)-PPAP (0.1 microM) displaced approximately 20-50% of total (+/-)-7-OH-[3H]DPAT binding in striatum, nucleus accumbens, and olfactory tubercle in autoradiographic studies, with the nucleus accumbens shell subregion exhibiting the greatest displacement. To determine directly (+)-7-OH-[3H]DPAT binding to sigma receptors, saturation analysis was performed in the cerebellum while masking D3 receptors with 1 microM dopamine. Under these conditions (+)-7-OH-[3H]DPAT labeled sigma receptors with an affinity of 24 nM. These results suggest that (a) (+/-)-7-OH-[3H]DPAT binds D3 receptors with high affinity in rat brain and (b) a significant proportion of (+/-)-7-OH-[3H]DPAT binding consists of sigma 1 sites and the percentages of these sites differ among the subregions of the striatum and nucleus accumbens.
Development of drugs for antimicrobial-resistant pathogens.

PURPOSE OF REVIEW Clinicians have noted an association between antimicrobial resistance and antimicrobial use since the introduction of these agents over 50 years ago. The problem of resistance becomes more pressing, however, when organisms acquire resistance mechanisms to multiple antimicrobial agents. Treatment options are limited for some multidrug-resistant organisms. Antimicrobial resistance is a driving force for the need for new antimicrobial agents, especially for these multidrug-resistant pathogens. At the same time, large pharmaceutical companies have indicated that they are devoting fewer resources to antimicrobial drug development. RECENT FINDINGS This article will review initiatives by the US Food and Drug Administration to identify problem pathogens for which drug development is of most public health importance, and to streamline the drug development process for antimicrobial agents. This article will also touch upon initiatives by federal agencies to implement programs to educate clinicians and the public on the appropriate use of antimicrobial agents to preserve the usefulness of currently marketed drugs. SUMMARY The most effective way to address the issues of antimicrobial resistance appears to be striking a balance between promoting new drug development and the prudent use of older agents to preserve the usefulness of currently marketed products.
The revenue-expenditure nexus: historical evidence for South Africa

Results from unit root and cointegration tests suggest that, allowing for structural breaks, government revenue and expenditure in South Africa during 1895-2005 were I(1) series and cointegrated. Results from Granger-type causality tests suggest that a bidirectional Granger-causal relation existed between revenue and expenditure for the full sample period and for sub-periods up to the 1960s, consistent with the so-called “fiscal synchronisation hypothesis”. However, in the 1960s the causal relation appears to have shifted to run from expenditure to taxation, consistent with Peacock and Wiseman's “displacement effect”. In the context of the recent fiscal consolidation literature, the South African fiscal experience would appear to be generally consistent with either revenue- or expenditure-led fiscal consolidation efforts, but with the more recent evidence favoring expenditure-led consolidations.
Play to learn: exploring online educational games in museums

How does one embed authentic learning outcomes in designing online educational games especially in a museum context? How does one design an online educational game so children can play to learn about museum objects and exhibits? These are challenging questions. In order to provide an authentic learning experience for today’s learners, the choice of developing online educational games becomes a popular direction in current museum media. In order to enhance learning and teaching in the museum context, a good online educational game requires good graphics, good character development, good content, and applies constructive learning theory in the development of the game. Marvin Christensen (1995), writes that a constructivist teaching and learning model calls for learning as: hands-on, minds-on, and authentic learning. He states that,
Carbon nanotube caps as springs: Molecular dynamics simulations

We present a detailed investigation of the spring behavior of carbon nanotube caps. We show that the caps act as harmonic springs, responding linearly to axial forces for appreciable displacements. Interestingly, we find the spring constant to be essentially independent of diameter and number of layers, but the maximum harmonic displacement increases with tube diameter and especially with number of layers. This spring effect is significant when the tubes are sufficiently short so that buckling does not occur before cap compression.
A novel synthesis of enantiomerically pure 5,5,5,5',5',5'-hexafluoroleucine.

A novel, short, and efficient synthesis of (S)-5,5,5,5‘,5‘,5‘-hexafluoroleucine (6) in greater than 99% ee starting from the protected oxazolidine aldehyde 1 is described. The enantiomeric excess of the product was calculated from an NMR analysis of a dipeptide formed by reaction with a protected l-serine derivative. Furthermore, a racemic sample of N-acylated hexafluoroleucine was enzymatically resolved by treatment with porcine kidney acylase I and was found to have the same optical rotation as a synthetic sample of 6.
The contribution of external service inputs to the product development efforts of small manufacturing firms

This paper examines the contribution of external inputs to the innovation performance of small manufacturing firms (SMFs) in New York State. Survey data from a 4-sector sample of SMFs is presented. Particular attention is given to recent patterns of external spending on technological, management, and information services. The results suggest that innovation performance is enhanced by external sources of scientific, technical, and professional support. SMFs with well developed internal technical skills are found to exhibit above average spending on external help. Elaborate patterns of external knowledge acquisition are found to be particularly prevalent among innovative firms that derive a substantial proportion of their current sales from new or significantly improved products. The empirical results are compared with the findings reported by other North American and European studies. The paper concludes with a discussion of the implication of the survey results for regional development agencies and R&D managers.
Multiple phase coexistence in finite systems.

Dynamic coexistence of several phaselike forms, a solid, microcrystalline phase, a homogeneously melted phase, and phases exhibiting a solid core and a melted surface, is found in isothermal molecular-dynamics simulations of magic-number rare-gas clusters. We present a theoretical model for the equilibrium and dynamics of phases of small systems that incorporates homogeneous and heterogeneous phases and gives necessary conditions for the material parameters if a cluster is to exhibit the observed multiple-phase behavior.
Cytogenetic, spectral karyotyping, fluorescence in situ hybridization, and comparative genomic hybridization characterization of two new secondary leukemia cell lines with 5q deletions, and MYC and MLL amplification

Cytogenetic studies of patients with therapy-induced acute myeloid leukemia (t-AML) have demonstrated whole chromosome loss or q-arm deletion of chromosomes 5 and/or 7 in a majority of cases. We have established two cell lines, SAML-1 and SAML-2, from two patients who developed t-AML after radiation and chemotherapy for Hodgkin disease. In both cases, the leukemia cells contained 5q deletions. SAML-1 has 58 chromosomes and numerous abnormalities, including der(1)(1qter1p22::5q315qter), der(5)(5pter5q22::1p221pter), +8, der(13)i(13)(q10)del(13)(q11q14.1), and t(10;11). Fluorescence in situ hybridization (FISH) with unique sequence probes for the 5q31 region showed loss of IL4, IL5, IRF1, and IL3, and translocation of IL9, DS5S89, EGR1, and CSFIR to 1p. SAML-2 has 45 chromosomes, del(5)(q11.2q31) with a t(12;13)ins(12;5), leading to the proximity of IRF1 and RB1, and complex translocations of chromosomes 8 and 11, resulting in amplification of MYC and MLL. Comparative genomic hybridization and spectral karyotyping were consistent with the G-banding karyotype and FISH analyses. Because a potential tumor suppressor(s) in the 5q31 region has yet to be identified, these cell lines should prove useful in the study of the mechanisms leading to the development of t-AML. © 2003 Wiley-Liss, Inc.
Gradient of the ZAPT2 energy

An explicit expression for the analytical first derivative of the Z-averaged perturbation theory taken to second order energy, due to Lee and Jayatilaka, is presented for application to high-spin systems described by a restricted open-shell Hartree–Fock wavefunction. The use of frozen core orbitals is incorporated into the derivation.
A Human XPC Protein Interactome—A Resource

Global genome nucleotide excision repair (GG-NER) is responsible for identifying and removing bulky adducts from non-transcribed DNA that result from damaging agents such as UV radiation and cisplatin. Xeroderma pigmentosum complementation group C (XPC) is one of the essential damage recognition proteins of the GG-NER pathway and its dysfunction results in xeroderma pigmentosum (XP), a disorder involving photosensitivity and a predisposition to cancer. To better understand the identification of DNA damage by XPC in the context of chromatin and the role of XPC in the pathogenesis of XP, we characterized the interactome of XPC using a high throughput yeast two-hybrid screening. Our screening showed 49 novel interactors of XPC involved in DNA repair and replication, proteolysis and post-translational modifications, transcription regulation, signal transduction, and metabolism. Importantly, we validated the XPC-OTUD4 interaction by co-IP and provided evidence that OTUD4 knockdown in human cells indeed affects the levels of ubiquitinated XPC, supporting a hypothesis that the OTUD4 deubiquitinase is involved in XPC recycling by cleaving the ubiquitin moiety. This high-throughput characterization of the XPC interactome provides a resource for future exploration and suggests that XPC may have many uncharacterized cellular functions.
Design aspects of attitude control systems

Figures of merit, besides those of performance, are discussed relative to the attitude control system of a vehicle capable of leaving and returning to the atmosphere. In addition to extreme changes in flight condition, these applications are subject to variations in configuration and performance requirements. Traditionally, control optimization has been concerned with minimizing or maximizing a variable system function such as error. Quite often these error criteria are replaced by other criteria such as invariance and the capacity for adaptability. In fact, during a complete mission including exit to re-entry it is desirable to utilize variable figures of merit. Examination of the control requirements of a modern returnable space vehicle illustrates how the various figures of merit dictate the design configuration. In those phases of the mission where self-adaptive control is employed, the figure of merit is usually determined by the particular technique selected. It is further demonstrated how the figure of merit varies with the mission phase as the control actuation configuration changes.
Stone Artifacts and Glass Tools from Enslaved African Contexts on St. Kitts’ Southeast Peninsula

St. Kitts, the first permanent English colony in the Caribbean, was dominated by sugar monoculture. During the island’s mid-eighteenth-century financial and political heights, the southeast peninsula was home to several sugar and cotton plantations. Recent excavations have recovered considerable data relating to the enslaved Africans who worked these plantations, including an assemblage of stone and glass tools. The stone tools, made from local chert, are dominated by cores, bifacial flakes, and utilized flakes, some of which are strike-a-lights or fire flints. The glass tools are primarily unifacial scrapers manufactured from bottle glass. Although enslaved African sites rarely contain more than a few of these artifacts, comparisons with sites in the USA and Caribbean suggest that chert and glass tool use among enslaved Africans was a widespread phenomenon rather than an isolated occurrence.
Personal exposure assessment to particulate metals using a paper-based analytical device

The development of a paper-based analytical device (PAD) for assessing personal exposure to particulate metals will be presented. Human exposure to metal aerosols, such as those that occur in the mining, construction, and manufacturing industries, has a significant impact on the health of our workforce, costing an estimated $10B in the U.S and causing approximately 425,000 premature deaths world-wide each year. Occupational exposure to particulate metals affects millions of individuals in manufacturing, construction (welding, cutting, blasting), and transportation (combustion, utility maintenance, and repair services) industries. Despite these effects, individual workers are rarely assessed for their exposure to particulate metals, due mainly to the high cost and effort associated with personal exposure measurement. Current exposure assessment methods for particulate metals call for an 8-hour filter sample, after which time, the filter sample is transported to a laboratory and analyzed by inductively-coupled plasma (ICP). The time from sample collection to reporting is typically weeks and costs several hundred dollars per sample. To exacerbate the issue, method detection limits suffer because of sample dilution during digestion. The lack of sensitivity hampers task-based exposure assessment, for which sampling times may be tens of minutes. To address these problems, and as a first step towards using microfluidics for personal exposure assessment, we have developed PADs for measurement of Pb, Cd, Cr, Fe, Ni, and Cu in aerosolized particulate matter.
A real-time stage Muskingum forecasting model for a site without rating curve

Abstract An adaptive model for on-line stage forecasting is proposed for river reaches where significant lateral inflow contributions occur. The model is based on the Muskingum method and requires the estimation of four parameters if the downstream rating curve is unknown; otherwise only two parameters have to be determined. As the choice of the forecast lead time is linked to wave travel time along the reach, to increase the lead time, a schematization of two connected river reaches is also investigated. The variability of lateral inflow is accounted for through an on-line adaptive procedure. Calibration and validation of the model were carried out by applying it to different flood events observed in two equipped river reaches of the upper-middle Tiber basin in central Italy, characterized by a significant contributing drainage area. Even if the rating curve is unknown at the downstream section, the forecast stage hydrographs were found in good agreement with those observed. Errors in peak stage and time...
Theoretical Perspectives and Empirical Evidence Relevant to Classroom Instruction with Manipulatives

The papers in this special issue focus on instructional strategies with manipulatives. Often described as “hands-on learning”, these strategies emphasize the use of physical and, more recently, virtual objects to represent target information and concepts. These strategies are frequently suggested as effective techniques for teaching across many domains of learning. This special issue presents contemporary theoretical perspectives and empirical evidence, regarding instructional manipulatives with a focus on application in classroom contexts. In this introduction, we present the primary topics of interest to the special issue and provide broad overviews of the contributors’ papers.
Examination of the effect of ethanol on human stratum corneum in vivo using infrared spectroscopy

Abstract Ethanol is generally believed to be a chemical capable of enhancing drug penetration across the skin. However, the mechanism by which ethanol achieves this effect has remained unclear. We have used Attenuated Total Reflectance Infrared (ATR-IR) spectroscopy to determine the action of ethanol on human stratum corneum (skin's barrier layer) in vivo. Treatment of the skin for thirty minutes with pure ethanol liquid (a) induced a transient decrease in the intensity and frequency of the C-H asymmetric stretching vibration (which originates from the acyl chains of the intercellular lipid domains of the stratum corneum), (b) caused observable increases in spectral absorbances associated with ethanol and (c) extracted appreciable amounts of lipid from the stratum corneum. These findings contradict the suggestion that ethanol “disorders” the intercellular lipid bilayers of the stratum comeum and reveal that ethanol enters the skin and removes measurable quantities of the barrier material. The changes induced by the short contact with ethanol are reversed within 24 h. Exposure of the stratum corneum to ethanol-saturated vapor again led to detectable partitioning of the alcohol into the stratum corneum. However, while no lipid extraction would occur in this experiment, there was, once more, no evidence for the induction of lipid disordering. We conclude that ethanol's ability to enhance drug penetration across the skin is the result, at least in part, of stratum corneum intercellular lipid removal.
TH2 cytokine-enhanced and TGF-β-enhanced vascular endothelial growth factor production by cultured human airway smooth muscle cells is attenuated by IFN-γ and corticosteroids

Abstract Background: T H 2 and T H 1 cytokines have opposite effects on many aspects of the inflammatory response. Methods: This study was designed to determine if cytokines possibly present in asthma can modulate airway smooth muscle cell (ASMC) production of vascular endothelial growth factor (VEGF) and thus contribute to altered airway vascularity. ASMC were incubated for 24 hours with various concentrations of T H 2 cytokines (IL-4, IL-5, IL-10, and IL-13); transforming growth factor (TGF)-β1, TGF-β2, or TGF-β3; and IL-1β or TNF-α with or without IFN-γ. Budesonide and exogenous prostaglandin (PG)E 2 were also evaluated. Postculture media were assayed for VEGF and PGE 2 by ELISA. Results: IL-4, IL-5, and IL-13 alone but not IL-10 enhanced VEGF production by ASMC in a concentration-dependent manner. IFN-γ alone inhibited spontaneous VEGF release by ASMC and concentration-dependently attenuated IL-4-augmented, IL-5-augmented, or IL-13-augmented production of VEGF ( P P P > .05). TNF-α alone had little effect on VEGF release by ASMC. Production of VEGF stimulated by all cytokines was inhibited by budesonide. Exogenous PGE 2 increased VEGF release, but cytokine modulation of PGE 2 release did not always correlate with VEGF release. Conclusions: T H 2 cytokines and TGF-β stimulate ASMC release of VEGF. This can be inhibited by IFN-γ and glucocorticoids. (J Allergy Clin Immunol 2003;111:1307-18.)
Role of hand contamination of personnel in the epidemiology of gram-negative nosocomial infections

Gram-negative organisms, responsible for a high rate of colonization and infection in an intensive, care nursery, were recovered frequently from hands of personnel, despite regular hand antisepsis. In sequential hand cultures contamination of hands by gram-negative organisms was transient in some nurses, but active multiplication of the organisms occurred on the hands of others and in a few nurses a temporary carrier state appeared, to exist. The results of this study suggest that the hands of hospital personnel may serve not only as a passive vehicle in the nosocomial transmission of gram-negative bacteria, but also may constitute a reservoir of nosocomial organisms.
Antioxidant treatment alters metabolism associated with internal browning in ‘Braeburn’ apples during controlled atmosphere storage

Abstract ‘Braeburn’ apple [Malus sylvestris var. domestica (Borkh.) Mansf] fruit can develop internal browning (Braeburn browning disorder; BBD) during hypoxic cold storage in elevated levels of CO2. Pre-storage treatment with the antioxidant diphenylamine (DPA) can prevent this disorder. To evaluate disorder-related metabolism, untargeted metabolic profiling using GC–MS and LC–MS was performed to characterize metabolism in cortex tissue of ‘Braeburn’ apple fruit treated with 2 g L−1 DPA or left untreated and stored under high CO2, controlled atmosphere (CA) storage of 1.5 kPa O2/3 kPa CO2 at 0.5 °C for up to 12 weeks. Partial least squares (PLS) regression analysis was employed to define metabolomic differences developing between untreated and DPA-treated fruit during storage and to identify metabolites linked with treatments, storage duration, and BBD. Metabolomes of control and DPA-treated fruit began to diverge at 1 week after storage and then oppositely diverge at 4 weeks after storage, which accompanied increased flesh browning in untreated fruit only. Flesh browning was associated with increased acetaldehyde, ethanol, and ethyl esters. DPA treatment reduced the levels of these and other volatile compounds. DPA treatment also reduced flesh content of many amino acids. These results indicate that metabolism is altered by DPA treatment and that these metabolic changes may be related to tissue integrity.
Characterization and dewatering evaluation of acid mine drainage sludge from ammonia neutralization

A major problem in the active treatment of acid mine drainage (AMD) is the generation of large volumes of sludge through pH neutralization and subsequent metal precipitation. The sludge typically contains a low concentration of solids, resulting in associated handling and disposal difficulties. Anhydrous ammonia is one reagent commonly used to neutralize AMD due to its quick reaction rate, easy implementation, and relatively low chemical and operational costs. However, very limited information is available in the literature related to the detailed characterization and dewaterability of ammonia-treated AMD sludge. In this study, sludge was collected from an AMD treatment facility where ammonia neutralization was used. The sludge characteristics included high pH and alkalinity, high total Fe and Al, elevated sulfate, and low solids content (0.72 ± 0.24%). Coagulants and flocculants were not effective in reducing the settled sludge volume. Based on filtration tests, ammonia-treated AMD sludge demonstrated re...
Martian Regolith X-ray Analyzer: Test Results of Geochemical Performance

Miniaturized x-ray spectrometers (two isotope sources, four proportional counter detectors) will be soft-landed on Mars in the 1975 Viking program for a “first look” at the planetary surface. In tests of analytical performance on unknown samples provided by the U.S. Geological Survey, 11 elements (Mg, Al, Si, K, Ca, Ti, Fe, Rb, Sr, Zr, and “O” [the sum of weight percents, elements of atomic number 1 through 11]) were detected and measured with accuracies which compare favorably with those obtained by wet-chemical methods. Upper concentrational limits were established for several other elements (including P, S, and Cl); limits also were established for CO 2 . Geochemical and petrologic interpretations derived from the x-ray results are in accord with similar interpretations based upon wet-chemical analyses of the unknown samples in three important respects: (1) determination of elemental differentiation trends, (2) determination of normative mineralogy and rock type, and (3) determination of critical parameters needed to resolve closely related geologic materials.
Parameters for Quantitative Comparison of Two-, Three-, and Four-Level Laser Media, Operating Wavelengths, and Temperatures

Several parameters are proposed for describing the statistical thermodynamic component of the exchange of photons between a pump and a laser beam. They are based on the occupation probability of absorbing and emitting, pump and laser levels, and are complementary to the optical cross sections. The ldquooccupation factor,rdquo f 0 , is appropriate for describing an optical amplifier in the small signal regime. f 1 is appropriate for describing an amplifier in the large signal regime, e.g., a laser. They serve to facilitate a quantitative comparison of laser gain media, operating temperatures, and choice of pump and laser wavelengths. After a simple scaling, both occupation factors have a numerical value that coincides well, in most cases, with conventional usage of the terms two-, three-, and four-level laser. They can thus serve as an unambiguous, quantitative alternative to the quasi-two-, quasi-three-, and quasi-four-level terminology. The proposed definitions are general enough to apply to many types of gain media, but are particularly useful for comparing systems with discrete levels, pumped with a narrowband source, in near-resonance with the laser wavelength. Several low-quantum-defect combinations of pump and laser wavelengths are analyzed for Er3+ , Nd3+ , Yb3+ , and Ho3+ in YAG, as a function of temperature.
Linezolid, Levofloxacin, and Vancomycin Against Vancomycin-Tolerant and Fluoroquinolone-Resistant Streptococcus pneumoniae in an In Vitro Pharmacodynamic Model

Study Objective. To compare the pharmacodynamic profiles of linezolid, levofloxacin, and vancomycin against clinical strains of Streptococcus pneumoniae, including vancomycin-tolerant and fluoroquinolone-resistant isolates. Design. In vitro pharmacodynamic model. Setting. Biosafety level 2, university research laboratory. Bacterial Strains. Ciprofloxacin-susceptible (79), ciprofloxacin-resistant (R921), and vancomycin-tolerant (P9802–020) clinical strains of S. pneumoniae. Intervention. An in vitro pharmacodynamic model was used to simulate standard dosing regimens of linezolid, levofloxacin, and vancomycin against the isolates 79, R921, and P9802–020. Measurements and Main Results. Bacterial density was profiled over 48 hours. Minimum inhibitory concentrations (MICs) for linezolid, levofloxacin, and vancomycin, respectively, were 1, 1, 0.5 μg/ml for isolate 79; 1, 4, 0.5 μg/ml for R921; and 0.5, 0.5, 0.5 μg/ml for P9802–020. Vancomycin minimum bactericidal concentration (MBC) values varied across large ranges for the tested strains. Linezolid achieved 99.9% kill against 79 and R921 by 24 and 28 hours, respectively. Levofloxacin achieved 99.9% kill against 79 and P9802–020 by 28 and 4 hours, respectively. Vancomycin achieved 99.9% kill against 79 and R921 by 8 and 24 hours, respectively. Levofloxacin did not demonstrate activity against R921 at the 48-hour end point. Minimal kill (< 2 log) at 48 hours was noted for vancomycin and linezolid against P9802–020. Conclusion. Vancomycin tolerance appeared to be more reliably characterized by persistent viability in time-kill analyses than by MBC:MIC ratios. Vancomycin exhibited bactericidal activity against the non-vancomycin-tolerant strains of S. pneumoniae. Linezolid exhibited both bactericidal and bacteriostatic activity against all three strains tested, whereas levofloxacin demonstrated bactericidal activity against the fluoroquinolone-susceptible isolates. Further investigation of treatment alternatives for infections due to vancomycin-tolerant S. pneumoniae are needed.
Theory of Slow Neutron Scattering by Liquids. I

Based on Van Hove's formalism, a general discussion of scattering in liquids has been given. The scattering cross section has been expressed in terms of velocity correlation functions; in particular, for the incoherent scattering cross section it is shown that in the Gaussian approximation for Van Hove's ${G}_{s}(\mathrm{r}, t)$ function, only a knowledge of the velocity autocorrelation function ${〈\mathrm{v}(0)\ifmmode\cdot\else\textperiodcentered\fi{}\mathrm{v}(t)〉}_{T}$ is necessary. The departure from the Gaussian approximation is expressed in terms of higher order velocity correlation functions. A derivation of an approximate formula for the width function of the Gaussian ${G}_{s}(\mathrm{r}, t)$, suggested earlier by the authors, has been given. The frequency spectrum of the velocity autocorrelation function has been introduced, and it has been shown that, as a consequence of the fluctuation-dissipation relations, the spectral representation of the width function is formally identical with that obtained earlier for a harmonic solid. The first few moments of the energy transfer have been discussed. Some of these moments have been shown to satisfy certain relations which involve only experimentally observable quantities; and hence, these relations can be used as a check on the internal consistency of the experimental data.
Dinoflagellate luminescence increases susceptibility of zooplankton to teleost predation

The “burglar alarm” theory of bioluminescence was investigated by determining predation rates of a nocturnal teleost predator,Porichthys notatus, on nonluminescent kelp mysids illuminated by dinoflagellate flashes, between the fall and spring of 1989/1990. Mysids (Holmesimysis costata) were placed in aquaria containing varying concentrations (0 to 40 cells/ml) of the dinoflagellatePyrocystis fusiformis and a single midshipman fish. Controls usedP. fusiformis during their luminescence-inhibited day phase. Mysid swimming movements readily stimulated dinoflagellate luminescence. Flashes and prey strikes were observed simultaneously by image-intensifying and infrared video cameras on a splitscreen monitor. Predation rates increased at dinoflagellate concentrations of 3 to 15 cells/ml and decreased below controls at levels>20 cells/ml. Videotape analysis showed that at low concentrations (2 to 5 cells/ml), strike success rates exceeded 75% if prey were previously illuminated by a flash, but dropped below 50% at higher cell densities. Increased predation was attributed to luminescence revealing prey position. The decrease at higher concentrations was considered to be due to greater flash frequency providing a more diffuse and confusing target. The study demonstrates the effects of secondary luminescence on zooplankton predation at normally encountered dinoflagellate concentrations.
Mast species composition alters seed fate in North American rodent-dispersed hardwoods

Interactions between plants and scatter-hoarding animals may shift from mutualism to predation as a function of the resources available to those animals. Because seed species differ in their nutrient content and defenses to predation, resource selection and cache management by scatter-hoarders, and thus seed fate, may also depend on the relative availability of different seed types. We tracked the fates of tagged Castanea dentata, Quercus alba, and Q. rubra seeds presented to rodents in pairwise combinations and found that C. dentata, which has moderate dormancy prior to germination, survived better in the presence of Q. alba (no dormancy) than with Q. rubra (longer dormancy). Decisions made by scatter-hoarders in response to the composition of available seed resources can alter the relationship between masting and seed dispersal effectiveness in individual tree species and may have influenced the evolution of asynchrony among species-specific masting patterns in temperate forests. In theory, preferential allocation of certain seed species to storage or consumption could also result in indirect apparent predation by one seed species on another.
An Evaluation of Two Methods for Assessment of MMH Activities

Two methods were evaluated for prediction of manual materials handling tasks using a bag as the container. In the first approach task variables of frequency and height of lift and dynamic strength of the subjects were used to predict lifting capacity of individuals for lifting bags from floor and knuckle height levels to shoulder height. The second approach utilized the same task variables along with several static strength measures. Evaluation of the developed models indicated that both approaches estimated lifting capacity with a reasonable degree of accuracy, however, the model containing the dynamic strength variable was found to predict lifting capacity with less error.
The Relationship between Mathematics Achievement and Spatial Abilities among Elementary School Children

Recent reviews by Fennema (1974) and Maccoby and Jacklin (1974) cite numerous studies in which males outperform females on tests of mathematical achievement and spatial ability. These sex differences are reported to occur starting in early adolescence and continuing on into adulthood. In Smith's analysis (1964) of spatial-ability studies, he concluded that spatial ability is positively related to high-level mathematical conceptualization, that is, people who can solve high-level mathematical problems generally have greater spatial ability than people who cannot solve these problems. Smith's assertion offers an explanation of why sex differences favoring males are often found concurrently on tests of mathematical achievement and spatial ability. Since most studies reviewed were conducted either at the secondary school or college level, the literature is not clear regarding the relationship between elementary school mathematics achievement and spatial abilities. Smith (1964) concluded from his analysis of the literature that spatial ability may have little to do with low-level mathematical conceptualization stressing simple calculation skills. However, except for Smith's writing, no other reports could be found to substantiate a relationship or a lack of relationship between low-level mathematics achievement and spatial abilities. The present study investigated the relationship between elementary school mathematics achievement (simple mathematics concepts and calculation skills) and highand low-level spatial abilities among males and females enrolled at the elementary school level. Low-level spatial abilities were defined as requiring the visualization of two-dimensional configurations, but no mental transformations of these visual images. High-level spatial abilities were characterized as requiring the visualization of threedimensional configurations, and the mental manipulation of these visual images. Based on Smith's writings (1964), it was expected that no substantial relationship would be found between mathematics achievement and highlevel spatial abilities among elementary school children. The literature provided no consistent basis to form an expectation regarding the relationship