cssi/SciSciGPT-SciSciNet huggingface dataset:
Calorimetric Determination of Energy Levels in Rare-Earth and Yttrium-Iron Garnets

It is shown that low-temperature calorimetry can be a sensitive method for determining the lowest excited energy levels in the rare-earth iron garnets. From Pauthenet's magnetization data one expects the lowest excited levels of several rare-earth ions to become populated at temperatures well below 20\ifmmode^\circ\else\textdegree\fi{}K and to contribute a large specific heat. This property offers the possibility of testing the validity of the Weiss molecular field and spin-wave approximations for this isomorphic series of oxides. After a discussion of the specific heat in terms of the Weiss molecular-field approximation, a spin-wave treatment for the garnets is then presented and the dispersion equation for the acoustical branch is derived. It is shown by a perturbation calculation that in garnets with magnetic rare-earth ions, there are twelve low-lying optical modes that will contribute to the specific heat below 20\ifmmode^\circ\else\textdegree\fi{}K. Heat-capacity measurements between 1.3 and 20.6\ifmmode^\circ\else\textdegree\fi{}K on the iron garnets of Y, Sm, Gd, Tb, Dy, Ho, Er, Yb, and Lu are presented and interpreted in terms of the two theoretical models. The energy levels so obtained are compared to those measured by optical absorption and deduced from magnetic data. For YIG and LuIG, where only the acoustical mode contributes to the magnetic specific heat, the result is compared to other heat-capacity and magnetic measurements. With the exception of TbIG and SmIG the magnetic specific heat of the garnets can be satisfactorily interpreted. Reasonable agreement is obtained in particular between the energy levels as deduced from specific heat data and those observed directly by optical absorption on YbIG and ErIG. In general it is found that for temperatures lower than$\ensuremath{\sim}\frac{{E}_{1}}{2{k}_{B}}$, where ${E}_{1}$ is the energy of the lowest excited level and ${k}_{B}$ the Boltzmann constant, the spin-wave approximation can be used to interpret the results, while for temperatures larger than about $\frac{{E}_{1}}{6{k}_{B}}$ the Weiss molecular-field treatment is valid. In the overlapping temperature range, both approximations are equally good. The nuclear magnetic specific heat for TbIG and HoIG is observed and is found to be consistent with the predictions from resonance measurements in other rare-earth compounds.
Free surface convection in a bounded cylindrical geometry

Abstract Surface tension-driven convection and buoyancy-driven convection in a bounded cylindrical geometry with a free surface are studied for a range of aspect ratios and Nusselt numbers. Linear theory and some aspects of a nonlinear analysis are utilized to determine the critical Marangoni and Rayleigh numbers, the structure of the convective motion, the direction of flow, and the nature of the bifurcation branching. The analysis is based on a somewhat different method for treating free convection problems, the use of Green's functions to reduce the problem to the solution of an integral equation.
MEMS capacitive flow sensor for natural gas pipelines

Abstract This paper presents the design, fabrication, and experimental results of an in-plane MEMS capacitive flow sensor that uses the displacement of a micro-fabricated paddle caused by dynamic gas pressure for measuring the velocity of the flow of surrounding gas. The fabrication process is simple; the prototype is fabricated on 100-μm device Silicon-On-Insulator wafers using only three photo-lithographic mask layers. The device area is 5.5 mm by 5.5 mm. A comb-drive capacitance is used as the transducer for the flow sensor. Measurements show that the output capacitance C is a quadratic function of the gas velocity v , C = k1 v 2 + k2 v + Cp, where k1 = −8.5 fF/(m/s)2, k2 = 73.6 fF/(m/s) and Cp = 16 pF. The advantage of using a capacitive sensing mechanism is that it is virtually insensitive to changes in ambient temperature. Experimental results show that the output capacitance changed only slightly, about 0.21–0.34%, when the temperature changed from 23 °C to 43 °C. Simplicity of fabrication, combined with insensitivity to variations in ambient temperature makes this sensor ideal for widespread deployment to monitor the flow in natural gas pipelines.
Value orientation and value profile of nigerian public managers: implications for management practice

Using England's personal value questionnaire the value orientations and value profile of public managers at the state level in Nigeria were analyzed. The analyses revealed that most of these managers have a pragmatic value orientation. Implications for management practice and management development in the Nigerian public sector were discussed. Future research directions were also suggested.
Neuron numbers and sizes in aging brain: comparisons of human, monkey, and rodent data.

One of the several sources of interest in aging animal brains is their potential as models of the aging human brain. In this review we examine whether neuron numbers and sizes change similarly in aging human, monkey and rodent brain regions which data are available from more than one species. The number of brain regions studied in more than one species is surprisingly limited. Some regions show correspondence in age-related changes between humans and selected animal models (primary visual cortex, CAI of hippocampus). For the majority of regions the data are conflicting, even within one species (e.g., somatosensory cortex, frontal cortex, cerebellum, cholinergic forebrain areas, locus coeruleus). Although some of the conflicting data may be attributed to procedural differences, particularly when data are expressed as density changes, much must be attributed to real species and/or strain differences in rodents. We conclude that neuron numbers and sizes may show similar age-related changes in human and animal brains only for sharply defined brain regions, animal species and/or strains, and age ranges.
Decomposition theory for multidisciplinary design optimization problems with mixed integer quasiseparable subsystems

Numerous hierarchical and nonhierarchical decomposition strategies for the optimization of large scale systems, comprised of interacting subsystems, have been proposed. With a few exceptions, all of these strategies are essentially heuristic in nature. Recent work considered a class of optimization problems, called quasiseparable, narrow enough for a rigorous decomposition theory, yet general enough to encompass many large scale engineering design problems. The subsystems for these problems involve local design variables and global system variables, but no variables from other subsystems. The objective function is a sum of a global system criterion and the subsystems’ criteria. The essential idea is to give each subsystem a budget and global system variable values, and then ask the subsystems to independently maximize their constraint margins. Using these constraint margins, a system optimization then adjusts the values of the system variables and subsystem budgets. The subsystem margin problems are totally independent, always feasible, and could even be done asynchronously in a parallel computing context. An important detail is that the subsystem tasks, in practice, would be to construct response surface approximations to the constraint margin functions, and the system level optimization would use these margin surrogate functions. The present paper extends the quasiseparable necessary conditions for continuous variables to include discrete subsystem variables, although the continuous necessary and sufficient conditions do not extend to include integer variables.
Dynamic renormalization-group theory of interfaces: Model A

The dynamics of the interface of an Ising-like system driven by relaxational dynamics is studied within the framework of a first-order \ensuremath{\epsilon} expansion near four dimensions. The starting point uses the static and dynamic equations of the bulk system (model A) and an interface is produced by imposing suitable boundary conditions. The interfacial dispersion relation is of the form ${\ensuremath{\omega}}_{q}$=-i\ensuremath{\Gamma}${q}^{z}$\ensuremath{\Omega}(q\ensuremath{\xi}), with z=2+O(${\ensuremath{\epsilon}}^{2}$) and \ensuremath{\Omega}(x) universal, and satisfies the Goldstone theorem for the spontaneously broken Euclidean symmetry.
In vitro synthesis of ACTH- and β-endorphin-related substances in the pars distalis of Anolis carolinensis

In order to investigate the biosynthesis of ACTH- and beta-endorphin-related substances in the pars distalis of Anolis carolinensis, explants of pars distali were incubated for 24 hr in a complete medium which contained [3H]tyrosine. Acid extracts of the incubates were immunoprecipitated with either an affinity-purified ACTH antiserum or an affinity-purified beta-endorphin antiserum and analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis. Three distinct peaks of ACTH-related material were detected. The major peak comigrated with human ACTH(1-39), while two minor peaks corresponded in apparent molecular weight to ACTH biosynthetic intermediate and precursor-sized material. Three peaks of beta-endorphin-related material were also detected. The major peak comigrated with beta-endorphin(1-31), while two minor peaks corresponded to beta-lipotropin (LPH) and precursor-sized material. Sequential immunoprecipitation experiments indicated that the precursor-sized material had antigenic determinants for both ACTH and beta-endorphin. In addition this peak was identical in apparent molecular weight to the common precursor for alpha-melanocyte-stimulating hormone (alpha-MSH) and beta-endorphin in the pars intermedia of A. carolinensis (R.M. Dores, Peptides 3, 925-935). Analysis of extracts of reptile pars distalis by gel-filtration chromatography revealed a single peak of naloxone-reversible opiate bioactivity which coeluted with the peak of beta-endorphin-sized immunoreactivity. On a molar basis there is tenfold more opiate bioactivity in the reptile pars distalis than in the reptile pars intermedia.
Spatial analysis of colorectal cancer incidence and proportion of late-stage in Massachusetts residents: 1995–1998

The aims of this study were to determine if observed geographic variations in colorectal cancer incidence are simply random or are statistically significant deviations from randomness, whether statistically significant excesses are temporary or persistent, and whether they can be explained by risk factors such as socioeconomic status (SES) or the percent of the population residing in an urban area rather than a rural area. Between 1995 and 1998, 6360 male and 6628 female invasive colorectal cancer cases were diagnosed in Massachusetts residents. Cases were aggregated to Census tracts and analyzed for deviations from random occurrence with respect to both location and time. Six geographic areas that deviated significantly from randomness were uncovered in the age-adjusted analyses of males: three with higher incidence rates than expected and eight lower than expected. In the age-adjusted analyses of females, one area with a higher incidence rate, and one area with a lower incidence rate than expected, were found. After adjustment for SES and percent urban, some of these areas were no longer significantly different. Public health practitioners can use the results of this study to focus their attention onto areas in Massachusetts that need to increase colorectal screening or have elevated risk of colorectal cancer incidence.
Social adaptation problems among Amerasian refugees

In this paper we describe and explain a variety of problems experienced by Amerasian youths upon their resettlement in the United States. We examine a matrix of contextual, household and individual behavioral predictors of Amerasian youths' problems and we argue that, taken individually, existing theoretical frameworks do not adequately explain the Amerasian adaptation process. The most significant predictors of Amerasian youths' problems are an unstable home environment, gender (maleness), whether or not the mother reported mental and physical problems, and the type of assistance provider (mutual assistance association). We add to existing research on Amerasians' process of adaptation by incorporating a wider variety of youths' problems into the dependent variable, by including hitherto unavailable independent variables into the analysis, and by suggesting some immediate strategies and new policy initiatives aimed at helping resettlement agencies deal with this specialized immigrant population. In sum, we demonstrate that Amerasians' unofficially mixed immigration status they are designated as immigrants who are treated as refugees but are simultaneously half-American - compounds theorists and policy makers' difficulties in dealing conceptually with this population
A Review of 99 Things Parents Wish They Knew Before® … Having “THE” Talk

Numerous books exist on parent-teen communication related to sex, sexuality, and sexual health. However, Chris Fariello and Pierre-Paul Tellier take a new, question-and-answer approach to reaching today's busy parents in their book 99 Things Parents Wish They Knew Before® … Having “THE” Talk. The concept behind the book is innovative, but the execution needs improvement. A revised, second edition is needed to address the clinical/colloquial language confusion, definitions of key words and concepts, and copy editing challenges.
Augmentation of Cav1 channel current and action potential duration after uptake of S100A1 in sympathetic ganglion neurons

S100A1, a 21-kDa dimeric Ca2+-binding protein of the EF-hand type, is expressed in cardiomyocytes and is an important regulator of heart function. During ischemia, cardiomyocytes secrete S100A1 to the extracellular space. Although the effects of extracellular S100A1 have been documented in cardiomyocytes, it is unclear whether S100A1 exerts modulatory effects on other tissues in proximity with cardiac cells. Therefore, we sought to investigate the effects of exogenous S100A1 on Ca2+ signals and electrical properties of superior cervical ganglion (SCG) neurons. Immunostaining and Western blot assays indicated no endogenous S100A1 in SCG neurons. Cultured SCG neurons took up S100A1 when it was present in the extracellular medium. Inside the cell exogenous S100A1 localized in a punctate pattern throughout the cytoplasm but was excluded from the nuclei. S100A1 partially colocalized with markers for both receptor- and non-receptor-mediated endocytosis, indicating that in SCG neurons multiple endocytotic pathways are involved in S100A1 internalization. In compartmentalized SCG cultures, axonal projections were capable of uptake and transport of S100A1 toward the neuronal somas. Exogenous S100A1 applied either extra- or intracellularly enhanced Cav1 channel currents in a PKA-dependent manner, prolonged action potentials, and amplified action potential-induced Ca2+ transients. NMR chemical shift perturbation of Ca2+-S100A1 in the presence of a peptide from the regulatory subunit of PKA verifies that S100A1 directly interacts with PKA, and that this interaction likely occurs in the hydrophobic binding pocket of Ca2+-S100A1. Our results suggest the hypothesis that in sympathetic neurons exogenous S100A1 may lead to an increase of sympathetic output.
Transposon insertion sequencing: a new tool for systems-level analysis of microorganisms

The combination of transposon mutagenesis with next-generation sequencing has emerged as a useful tool for identifying putative gene function in a high-throughput manner. Here, van Opijnen and Camilli describe the four main techniques that are used for this purpose, with a focus on their application for uncovering bacterial gene function. Our knowledge of gene function has increasingly lagged behind gene discovery, hindering our understanding of the genetic basis of microbial phenotypes. Recently, however, massively parallel sequencing has been combined with traditional transposon mutagenesis in techniques referred to as transposon sequencing (Tn-seq), high-throughput insertion tracking by deep sequencing (HITS), insertion sequencing (INSeq) and transposon-directed insertion site sequencing (TraDIS), making it possible to identify putative gene functions in a high-throughput manner. Here, we describe the similarities and differences of these related techniques and discuss their application to the probing of gene function and higher-order genome organization.
Protein kinase C Beta in the tumor microenvironment promotes mammary tumorigenesis.

Protein kinase C beta (PKCβ) expression in breast cancer is associated with a more aggressive tumor phenotype, yet the mechanism for how PKCβ is pro-tumorigenic in this disease is still unclear. Interestingly, while it is known that PKCβ mediates angiogenesis, immunity, fibroblast function and adipogenesis, all components of the mammary tumor microenvironment (TME), no study to date has investigated whether stromal PKCβ is functionally relevant in breast cancer. Herein, we evaluate mouse mammary tumor virus-polyoma middle T-antigen (MMTV-PyMT) induced mammary tumorigenesis in the presence and absence of PKCβ. We utilize two model systems: one where PKCβ is deleted in both the epithelial and stromal compartments to test the global requirement for PKCβ on tumor formation, and second, where PKCβ is deleted only in the stromal compartment to test its role in the TME. MMTV-PyMT mice globally lacking PKCβ live longer and develop smaller tumors with decreased proliferation and decreased macrophage infiltration. Similarly, when PKCβ is null exclusively in the stroma, PyMT-driven B6 cells form smaller tumors. These experiments reveal for the first time a tumor promoting role for stromal PKCβ in MMTV-PyMT tumorigenesis. In corroboration with these results, PKCβ mRNA (Prkcb) is increased in fibroblasts isolated from MMTV-PyMT tumors. These data were confirmed in a breast cancer patient cohort. Combined these data suggest the continued investigation of PKCβ in the mammary TME is necessary to elucidate how to effectively target this signaling pathway in breast cancer.
Electric field modulation of the fluorescence from Rhodobacter sphaeroides reaction centers

Abstract The fluorescence intensity from randomly oriented Rhodobacter (Rb.) sphaeroides photosynthetic reaction centers at 77 K increases in an applied electric field. This is ascribed to a net reduction in the rate of the initial electron transfer reaction which competes with fluorescence due to the effect of the field on the free energy of charge separation. Quantitative analysis of the fluorescence change in an electric field indicates that the difference in permanent dipole moment between the ground and initially formed excited state is greater than between the ground and emitting state.
Insights into Mechanism of Glucokinase Activation: OBSERVATION OF MULTIPLE DISTINCT PROTEIN CONFORMATIONS.

Human glucokinase (GK) is a principal regulating sensor of plasma glucose levels. Mutations that inactivate GK are linked to diabetes, and mutations that activate it are associated with hypoglycemia. Unique kinetic properties equip GK for its regulatory role: although it has weak basal affinity for glucose, positive cooperativity in its binding of glucose causes a rapid increase in catalytic activity when plasma glucose concentrations rise above euglycemic levels. In clinical trials, small molecule GK activators (GKAs) have been efficacious in lowering plasma glucose and enhancing glucose-stimulated insulin secretion, but they carry a risk of overly activating GK and causing hypoglycemia. The theoretical models proposed to date attribute the positive cooperativity of GK to the existence of distinct protein conformations that interconvert slowly and exhibit different affinities for glucose. Here we report the respective crystal structures of the catalytic complex of GK and of a GK-glucose complex in a wide open conformation. To assess conformations of GK in solution, we also carried out small angle x-ray scattering experiments. The results showed that glucose dose-dependently converts GK from an apo conformation to an active open conformation. Compared with wild type GK, activating mutants required notably lower concentrations of glucose to be converted to the active open conformation. GKAs decreased the level of glucose required for GK activation, and different compounds demonstrated distinct activation profiles. These results lead us to propose a modified mnemonic model to explain cooperativity in GK. Our findings may offer new approaches for designing GKAs with reduced hypoglycemic risk.
Fast rational function fitting of broadband multi-port responses via repeated random sampling

A methodology is presented for the computationally-efficient and accurate rational approximation of broadband electromagnetic responses of passive multi-ports. The proposed method relies on the repeated rational interpolation of subsets of the frequency data with the number of samples in each set being a fraction of that in the original set. The generated poles from the subsets are appropriately combined to serve as the poles of the multi-port system and to solve for the residues of its rational function fit. The expediency of this methodology is demonstrated through its application to the fitting of several multi-port broadband data.
Dynamics of rigid and flexible polymer chains in confined geometries. part I: steady simple shear flow

Abstract This paper describes exact solutions to the response of both the elastic and rigid dumbbell models to a steady simple shear flow in a channel having a length scale comparable to the dumbbells themselves. Results are given for rheological properties over the entire range of the ratio of the channel width to the length of the dumbbell. It is found that both models lead to a decrease in viscosity as the channel is reduced in size with the elastic dumbbell predicting a stronger dependence on that parameter compared with the rigid dumbbell. The elastic dumbbell predicts shear independent rheological properties whereas the rigid dumbell predicts shear thinning as in the case of unbounded flows. The rate of shear thinning, however, decreases with decreasing channel width.
Role of the air-water interface in the retention of TiO2 nanoparticles in porous media during primary drainage.

The increasing use of nanomaterials in commercial products has resulted in increased concerns about their potential environmental impacts. The overall mobility of nanomaterials in the environment may depend in part on their mobility in the unsaturated zone of the subsurface, which may provide a sink for nanomaterials, preventing their spread, or a long-term contaminant source. The objective of this work was to study the dynamic unsaturated transport of titanium dioxide (TiO2) during primary drainage to examine the role of air–water interface formation on nanomaterial retention. A specialized automated system was used to track depletion of TiO2 in the pore solution of a porous medium during dynamic drainage, while simultaneously measuring capillary pressure (Pc) and saturation (S). A continuous mass balance was used to calculate the mass of retained TiO2 nanoparticles. Experiments were specifically designed to minimize TiO2 interactions with solid surfaces to allow direct assessment of the role of the air–...
Effect of solute misfit and temperature on irradiation-induced segregation in binary Ni alloys☆

Abstract Four solid-solution, binary alloys of 1 at.% Al, Ti, Mo and Si in Ni were irradiated with 3.5-MeV Ni + ions at temperatures between 385 and 660° C. Auger analysis of the solute concentration as a function of depth shows that the oversize solutes, Al, Ti and Mo, are depleted near the irradiated surface, whereas the undersize solute, Si, is enriched. The magnitude of this irradiation-induced segregation in the Ni-1 at.% Si alloy is sufficient to cause precipitation of a surface layer of Ni 3 Si after a total dose of 5 dpa near 600° C; the segregation diminishes at both lower and higher temperatures. The observed temperature dependence is in qualitative agreement with a recently proposed theory of irradiation-induced solute segregation, but quantitative differences exist.
FOXO1 Deletion Reduces Dendritic Cell Function and Enhances Susceptibility to Periodontitis

The host response plays both protective and destructive roles in periodontitis. FOXO1 is a transcription factor that is activated in dendritic cells (DCs), but its function in vivo has not been examined. We investigated the role of FOXO1 in activating DCs in experimental (CD11c.Cre+.FOXO1L/L) compared with matched control mice (CD11c.Cre−.FOXO1L/L) in response to oral pathogens. Lineage-specific FOXO1 deletion reduced the recruitment of DCs to oral mucosal epithelium by approximately 40%. FOXO1 was needed for expression of genes that regulate migration, including integrins αν and β3 and matrix metalloproteinase-2. Ablation of FOXO1 in DCs significantly decreased IL-12 produced by DCs in mucosal surfaces. Moreover, FOXO1 deletion reduced migration of DCs to lymph nodes, reduced capacity of DCs to induce formation of plasma cells, and reduced production of bacteria-specific antibody. The decrease in DC function in the experimental mice led to increased susceptibility to periodontitis through a mechanism that involved a compensatory increase in osteoclastogenic factors, IL-1β, IL-17, and RANKL. Thus, we reveal a critical role for FOXO1 in DC recruitment to oral mucosal epithelium and activation of adaptive immunity induced by oral inoculation of bacteria.
Structural Characterization of Integrated II–VI and III–V Heterostructures for Solar Cell Applications

We report on the microstructural characterization of monolithically integrated II–VI and III–V heterostructures that are being developed for possible solar cell applications. Observations by transmission electron microscopy have shown that the growth of lattice-matched ZnTe layers on GaSb(100) substrates resulted in very high quality interfaces and very few structural defects. We then investigated short-period superlattices (SSLs) of CdSe and CdTe digital alloys grown using ZnTe buffer layers on GaSb substrates. The effect of rapid thermal annealing was also studied. High-resolution electron micrographs showed that the CdSe-CdTe SSL had very high quality for approximately 25–50 periods closest to the substrate but that considerable stacking faults and microtwins were visible in layers near the top surface of the sample. For comparison purposes, CdSe layers grown on InAs(100) substrates, again using ZnTe as a buffer layer, were also characterized. The quality of the CdSe layer was not as good as that observed in the SSL sample, possibly because of the larger lattice mismatch between the materials.
Control of dissolution rates of orthosilicate minerals by divalent metal–oxygen bonds

COMMON rock-and soil-forming minerals are complicated structures of varying composition. Despite some encouraging progress1,2 there is as yet no comprehensive rationale for predicting the dissolution rates of these minerals. Here we test the hypothesis3 that dissolution rates of compositionally distinct orthosilicate minerals scale in a fashion similar to rates of water exchange around the corresponding dissolved, divalent cation. Although dissolution rates span several orders of magnitude, the hypothesis is sustained. Minerals containing alkaline-earth cations dissolve at rates that correlate with ionic size, whereas minerals containing first-row transition metals dissolve at rates that vary with the number of cationd-electrons. Both types of behaviour are consistent with the control of dissolution rate by the character of the bonds between the divalent cation and neighbouring oxygen atoms. This result supports the proposed link3–6 between the mechanisms of mineral dissolution and the mechanisms by which a dissolved metal exchanges ligands. With this link it may be possible to predict dissolution rates for other nearly isostructural minerals that vary in composition.
Abraham Lincoln’s Presidency as the Foundation of the Modern Administrative State?

S o much has been written about Abraham Lincoln's presidency that it is nothing short of courageous to devote yet another study to it. Of the myriad topics that have dominated this literature thus far (e.g., the Lincoln-Douglas debates, the abolition of slavery, the speeches and papers, the suspension of habeas corpus, the assassination, the cabinet politics), Doris Kearns Goodwin chose to focus in Team of Rivals on the skill with which Lincoln managed to navigate the many conflicting political forces of his time without losing the support of key players.
Primary production, new production and vertical flux in the eastern Pacific Ocean

The sinking of participate organic matter in the ocean links food webs beneath the euphotic zone to surface primary production and is an important pathway for the downward transport of many elements1–3. The flux of particulate organic carbon (POC) is also an important parameter in the global carbon cycle and may be related to long-term changes in atmospheric CO2 4,5. In 1980, Suess6 synthesized existing measurements from sediment trap studies into a model to predict the vertical flux of POC from depth (z) and primary production (PP)6. The Suess model has become the standard for evaluating vertical flux data7, for estimating the annual flux of POC in the ocean8 and for parameterizing ocean carbon cycle models4,5. We present here a new model of the vertical flux of POC and particulate organic nitrogen (PON) from a set of contemporaneous measurements of PP and fluxes made during the VERTEX (Vertical Transport and Exchange) programme in the north-east Pacific. The VERTEX model indicates that PP and vertical fluxes of POC and PON, in the oligotrophic ocean are greater than previously suggested. In addition, the vertical flux of PON from the photic zone represents a measure of the PP that is supported by new nitrogen (new production)9,10. In the north-east Pacific, new production ranged from 13 to 25% of primary production and was positively related to total PP.
Mechanism Analysis of FTIR Absorption Characteristic of MgO Nano-Powder

Nano-MgO powders with different size form 30 to 100 nm are prepared and measured by XRD and IR. FTIR results show that nano-MgO powder has abnormal infrared absorption behaviors compared with that of micron scale; and there exist blue shifts of infrared absorption peaks with the decrease of the particles size. But when the average particle size of nano-MgO powder is down to less than 50 nm, there are red shifts of infrared absorption peaks. The aim of the paper is to analyze the mechanism of IR absorption characteristic of MgO Nano-powder by a single- dimensional chain vibration model.
Intercellular Communication, Homeostasis, and Toxicology

The article highlighted in this issue is "Inhibition of Gap Junctional Intercellular Communication by Perfluorinated Compounds in Rat Liver and Dolphin Kidney Epithelial Cell Lines in Vitro and Sprague-Dawley Rats in Vivo" by W. Hu, P. D. Jones, B. L. Upham, J. E. Trosko, C. Lau, and J. P. Giesy (pp. 429-436).
Persistence of streptomycin resistance during subcultures in streptomycin free media.

SummaryEach of 13 strains of gramnegative bacilli that were highly resistant to streptomycin was passed through 100 serial subcultures in broth. Evidence was obtained which indicated that appreciable numbers of streptomycin sensitive cells appeared in 2 of these strains: in one instance after 28 subcultures and in the other after 59 transfers. The 11 remaining strains appeared to retain their resistance.
Modeling of Vesiculation in Healthy and Defective Human Erythrocyte Membrane

We apply a two-component coarse-grained molecular dynamics (CGMD) red blood cell (RBC) membrane model which includes an explicit representation of the spectrin network, the lipid bilayer, and the band-3 proteins, to simulate vesiculation in the RBC membrane. We investigate vesiculation induced by the spontaneous curvature of the membrane domain and vesiculation induced by a stiffened cytoskeleton causing compression on the lipid bilayer. In addition, we model vesiculation in RBCs from patients suffering from the blood disorders of hereditary spherocytosis (HS) and elliptocytosis (HE). Our simulation results show that the spontaneous curvature of a membrane domain induces vesicles with a diameter less than 50 nm. We also found that compression on the membrane can cause the formation of vesicles having heterogeneous composition with a size similar to the size of the cytoskeleton corral. When both effects are taken into consideration, the compression on the membrane can facilitate the formation of vesicles originated from the membrane domain with the same spontaneous curvature. While the size of the vesicles induced by the compression in the normal RBC membrane is similar to the cytoskeleton corral size, the vesicle sizes become more diverse in HS RBCs because the constrain from the cytoskeleton on the lipid bilayer is reduced. When the vertical connectivity between the lipid bilayer and the cytoskeleton is elevated, multiple vesicles, with sizes similar to the cytoskeleton corral dimension, are generated from the compressed membrane. However, membrane with low vertical connectivity tends to produce larger vesicles under the same compression ratio as above. In HE RBCs, the reduced cytoskeleton connectivity facilitates the membrane vesiculation. It is noted that vesicles released from the HE RBCs could contain spectrin filaments while vesicles released from the HS RBCs are depleted of cytoskeleton components.
Analysis of Heat Transfer in Surimi Paste Heated by Conventional and Ohmic Means

Abstract Heating of surimi paste was studied to determine the effects of conventional (water-bath) cooking vs. ohmic (electrical resistance) cooking. Results of both experiments and models were observed over the cooking temperature range for Pacific whiting surimi paste having a salt content of 2% and moisture contents of 74% and 80%. A good correlation between model and experiment resulted using a finite element analysis. Ohmic heating under a high voltage gradient (1200 V/m) resulted in a heating rate 11 times higher than that of conventional (90°C water bath) heating for a cylindrical sample of 19 mm diameter. Results also showed the significant effects of the two heating mechanisms upon the time during which the sample center dwells within the critical enzyme activity range. The effects of voltage gradient across the sample, moisture content, heat exchange with the surrounding ambients, and electrode design were also investigated. Heat leakage to the sample holder and surroundings caused a significant...
Influence of form and quantity of selenium on the development and survival of an insect herbivore.

Abstract Even plants classified as ‘nonaccumulators’ can sequester concentrations of sodium selenate, sodium selenite, selenocystine and selenomethionine that can strongly influence insect development and survival. These forms of selenium (Se), tested in diet-incorporation bioassays, proved toxic to larvae of a generalist insect herbivore at relatively low levels. Sodium selenite was the most toxic form tested against Spodoptera exigua (Hubner), with an LC 50 of 9.14 μg g −1 wet wt (21.11 μg g −1 dry wt). Selenocystine was intermediate with an LC 50 of 15.2 μg g −1 wet wt. The least toxic forms, sodium selenate and selenomethionine, had LC 50 s below 50 μg g −1 dry wt, the upper level for tissues of plants classified as nonaccumulators. Ingestion of some forms of Se also affected growth and development. Increasing concentrations of sodium selenate and sodium selenite decreased pupal weight and added significantly to the time needed for development to the pupal and adult stages. The time required to complete the larval stage increased by over 25% and the time from egg to adult emergence was extended by 22% to nearly 30%. Selenocystine and selenomethionine did not significantly increase developmental times, even at concentrations that killed 90% or more of the test populations. Analyses of relative growth rate, relative growth index, and an analysis of covariance technique for measuring growth indicated that the form of Se affected growth rates, growth inhibition responses of the larvae, and toxicological effects. Thus, quantity and the form of Se accumulating in plants grown on Se-contaminated sites are likely to influence the population dynamics of insect herbivores. The implications of these results for the ecology of contaminated sites are discussed.
Photoacoustic determination of fluorescent quantum yields of protein probes

Pulsed-laser photoacoustic methods may be used to determine the fluorescent quantum yields of fluorophores in solution. Of interest to biological spectroscopists are the fluorescent quantum yields of probes bound covalently or noncovalently to proteins. Previous studies (J.R. Small et al., Fluorescence Detection III, E.R. Menzel, ed., SPIE Proceedings 1054, pp. 26-35, 1989) have been extended to examine some common protein probes and their fluorescent quantum yields. Examples include the probes Prodan [6-propionyl-2-(dimethylamino)naphthalene] and Acrylodan [6- acryloyl-2-(dimethylamino)naphthalene] in a variety of protein and solvent environments. We have found that, at the simplest level, the pulsed-laser photoacoustic technique gives us excellent results for the fluorescent quantum yields of fluorophores free in solution, but interestingly anomalous results for the fluorophores bound to proteins. The source of the anomalous protein results has not yet been determined, but several possibilities are discussed.
Theological fatalism and modal confusion

L'A. examine de recents arguments en faveur du fatalisme theologique (la prescience divine est incompatible avec la liberte humaine)
Constitutive mass balance relations between chemical composition, volume, density, porosity, and strain in metasomatic hydrochemical systems: Results on weathering and pedogenesis

Relations characterizing the chemical, physical, and mechanical changes resulting from metasomatic hydrochemical processes are developed using mass balance models which formally link chemical composition to bulk density, mineral density, volumetric properties, porosity, and amount of deformation (strain). Rigorous analysis of aqueous solute transport effects is then made possible in a variety of porous media flow environments including chemical weathering, pedogenesis (soil formation), diagenesis, ore deposition and enrichment, and metamorphism. Application of these linear constitutive relations to chemical weathering profiles shows that immobile and locally mobile chemical elements, with masses conserved on the scale of soil profiles, can be accurately identified from analysis of appropriate data arrays and then used as natural geochemical tracers to infer the nature and extent of hydrochemical weathering processes and volume changes during pedogenesis. Assumptions commonly made in the past about the supposed immobility of certain elements, e.g., Ti and Zr, become unnecessary. Quantitative differentiation between the effects of residual and supergene fractionation is then easily made. These methods are applied to Ni-rich laterites developed by weathering of ultramafic rocks, showing that during ordinary residual enrichment, Ni is concentrated by as much as 4× protolith peridotite concentrations. This occurs simply by silicate mineral dissolution and removal of chemical elements other than Ni (e.g., Mg) with a corresponding reduction in saprolite density and increase in bulk porosity without significant deformation. In contrast, laterites with mineable concentrations of Ni which are similarly undeformed (such as the Nickel Mountain Mine in Riddle, Oregon) have experienced, in addition to residual enrichment, strong supergene enrichment by fractionation of ore elements between a leached zone from which Ni is extracted and a complementary enriched zone positioned farther along the direction of ground water flow. Soil-forming processes in podzol chronosequences developed on sandy beach terraces of the Mendocino Coast of California involved soil column collapse of 60 percent by dissolution of silicate minerals in the albic horizon of Al and Fe leaching, and 70 percent dilation (expansion) in the overlying organic-rich layer by root growth. The amount of erosion based upon paleosurface reconstructions using the excess mass of Fe, Al, Pb, Ga, and Cu in the zone of supergene enrichment (spodic horizon) below the ground water table indicates that subsurface erosion by dissolutional collapse is three times that of surficial erosion. Finally, using published chemical data for Ti, Zr, and Cr on major bauxite deposits in Australia where erosion rates are thought to be low, we infer that there may have been major amounts of dissolutional collapse to explain the upwards increase of detrital zircon and rutile in weathering profiles.
Model-Eliciting Activities: A Research-Based Method for Inquiry Learning and Professional Development in the Engineering Classroom

Attracting students to engineering is a challenge. In addition, ABET requires that engineering graduates be able to work on multi-disciplinary teams and apply mathematics and science when solving engineering problems. One manner of integrating teamwork and engineering contexts in a first-year foundation engineering course is through the use of Model-Eliciting Activities (MEAs) — realistic, client-driven problems based on the models and modeling theoretical framework. A Model-Eliciting Activity (MEA) is a real-world client-driven problem. The solution of an MEA requires the use of one or more mathematical or engineering concepts that are unspecified by the problem — students must make new sense of their existing knowledge and understandings to formulate a generalizable mathematical model that can be used by the client to solve the given and similar problems. An MEA creates an environment in which skills beyond mathematical abilities are valued because the focus is not on the use of prescribed equations and algorithms but on the use of a broader spectrum of skills required for effective engineering problem-solving. Carefully constructed MEAs can begin to prepare students to communicate and work effectively in teams; to adopt and adapt conceptual tools; to construct, describe, and explain complex systems; and to cope with complex systems. MEAs provide a learning environment that is tailored to a more diverse population than typical engineering course experiences as they allow students with different backgrounds and values to emerge as talented, and that adapting these types of activities to engineering courses has the potential to go beyond “filling the gaps” to “opening doors” to women and underrepresented populations in engineering. Further, MEAs provide evidence of student development in regards to ABET standards. Through NSF-funded grants, multiple MEAs have been developed and implemented with a MSE-flavored nanotechnology theme. This paper will focus on the content, implementation, and student results of one of these MEAs.Copyright © 2008 by ASME
Multiple exciton dissociation and hot electron extraction by ultrafast interfacial electron transfer from PbS QDs

Abstract In addition to size dependent optical properties, strong quantum confinement in semiconductor nanoparticles (QDs) also affects their exciton relaxation, annihilation and dissociation dynamics, leading to their potential applications in third generation solar energy conversion devices. Multiple exciton generation and hot electron extraction have been proposed as potential approaches to increase the solar conversion efficiencies beyond the Shockley–Queisser limit in QD based solar cells. A common challenge faced by these two approaches is the need for ultrafast exciton dissociation to compete with ultrafast carrier cooling and exciton annihilation. In this review, we summarize our recent studies on multiple exciton generation and dissociation dynamics in PbS-MB + complexes as well as strong electronic coupling and ultrafast electron transfer from PbS QDs to TiO 2 nanocrystalline thin films. In PbS-MB + complexes, we demonstrate that the multiple exciton generation efficiency in PbS QDs are unaffected by the presence of electron acceptors, and the multiple excitons can be fully dissociated by these acceptors via ultrafast electron transfer. For PbS QDs on TiO 2 nanocrystalline films, we observe strong electronic coupling induced broadening of the 1S exciton band, which indicates a ∼6 fs electron transfer process according to the Newns–Anderson model of chemisorption. This transfer time is faster than the reported hot electron relaxation time (a few hundred femtosecond), which suggests the feasibility of hot electron extraction prior to their relaxation in these materials.
Tropical convection, ionospheric potentials and global circuit variation

The ionospheric potential (VI), a measure of the earth's overall electric field intensity, correlates with the classic 'Carnegie curve' diurnal variation in electric field caused by the global distribution of thunderstorms. A comparison of VI variation with satellite images of high tropical cloud fields indicates that equatorial thunderstorms over the continents are dominant in maintaining the earth's electric field. VI time series obtained at just one location may provide a high-resolution measure of intense tropical convection.
An Analysis of Water Management for a PEM Fuel Cell System in Automotive Drive Cycles

Low-temperature operation of a Proton Exchange Membrane (PEM) fuel cell system requires humidification of the membrane. The amount of water produced electrochemically within the fuel cell system is directly related to the system power output. In a vehicular application where the power output may vary substantially over time, it is critical that water management be addressed in the fuel cell and vehicle system design. This paper introduces the integration of a detailed fuel cell system model within a hybrid electric vehicle system model. The newly integrated models provide the capability to better understand the impacts of a variety of fuel cell and vehicle design parameters on overall system performance. Ultimately, coupling these models leads to system optimization and increased vehicle efficiency. This paper presents the initial results of a parametric study to quantify the impacts of condenser size and cathode inlet relative humidity on system water balance under realistic drive cycles in a fuel cell hybrid electric sport utility vehicle. The vehicle simulations included operation under both hot and ambient start conditions. The study results demonstrate that ambient start or aggressive drive cycles require larger condensers or water reservoirs to maintain a neutral water balance than either hot start or less aggressive drive cycles.Copyright © 2003 by ASME